diff --git a/Cargo.lock b/Cargo.lock
index 2ab5185..8200cd9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1110,11 +1110,13 @@ dependencies = [
  "erased-serde",
  "indicatif",
  "log",
+ "md5",
  "once_cell",
  "pimalaya-email",
  "pimalaya-keyring",
  "pimalaya-process",
  "pimalaya-secret",
+ "rusqlite",
  "serde",
  "serde_json",
  "shellexpand",
@@ -2066,7 +2068,7 @@ dependencies = [
 [[package]]
 name = "pimalaya-email"
 version = "0.7.1"
-source = "git+https://git.sr.ht/~soywod/pimalaya#4fc9ef469ddb89728c42b13bbff928266307ed9b"
+source = "git+https://git.sr.ht/~soywod/pimalaya#715546fabf7246a7f4bff8371aff77f116ae9b9a"
 dependencies = [
  "advisory-lock",
  "ammonia",
@@ -2108,7 +2110,7 @@ dependencies = [
 [[package]]
 name = "pimalaya-keyring"
 version = "0.0.1"
-source = "git+https://git.sr.ht/~soywod/pimalaya#4fc9ef469ddb89728c42b13bbff928266307ed9b"
+source = "git+https://git.sr.ht/~soywod/pimalaya#715546fabf7246a7f4bff8371aff77f116ae9b9a"
 dependencies = [
  "keyring",
  "log",
@@ -2118,7 +2120,7 @@ dependencies = [
 [[package]]
 name = "pimalaya-oauth2"
 version = "0.0.1"
-source = "git+https://git.sr.ht/~soywod/pimalaya#4fc9ef469ddb89728c42b13bbff928266307ed9b"
+source = "git+https://git.sr.ht/~soywod/pimalaya#715546fabf7246a7f4bff8371aff77f116ae9b9a"
 dependencies = [
  "log",
  "oauth2",
@@ -2130,7 +2132,7 @@ dependencies = [
 [[package]]
 name = "pimalaya-process"
 version = "0.0.1"
-source = "git+https://git.sr.ht/~soywod/pimalaya#4fc9ef469ddb89728c42b13bbff928266307ed9b"
+source = "git+https://git.sr.ht/~soywod/pimalaya#715546fabf7246a7f4bff8371aff77f116ae9b9a"
 dependencies = [
  "log",
  "thiserror",
@@ -2139,7 +2141,7 @@ dependencies = [
 [[package]]
 name = "pimalaya-secret"
 version = "0.0.1"
-source = "git+https://git.sr.ht/~soywod/pimalaya#4fc9ef469ddb89728c42b13bbff928266307ed9b"
+source = "git+https://git.sr.ht/~soywod/pimalaya#715546fabf7246a7f4bff8371aff77f116ae9b9a"
 dependencies = [
  "log",
  "pimalaya-keyring",
diff --git a/Cargo.toml b/Cargo.toml
index f9d157c..d8c4700 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -50,11 +50,16 @@ env_logger = "0.8"
 erased-serde = "0.3"
 indicatif = "0.17"
 log = "0.4"
+md5 = "0.7.0"
 once_cell = "1.16.0"
 pimalaya-email = { git = "https://git.sr.ht/~soywod/pimalaya" }
 pimalaya-keyring = { git = "https://git.sr.ht/~soywod/pimalaya" }
 pimalaya-process = { git = "https://git.sr.ht/~soywod/pimalaya" }
 pimalaya-secret = { git = "https://git.sr.ht/~soywod/pimalaya" }
+# pimalaya-email = { path = "/home/soywod/sourcehut/pimalaya/email" }
+# pimalaya-keyring = { path = "/home/soywod/sourcehut/pimalaya/keyring" }
+# pimalaya-process = { path = "/home/soywod/sourcehut/pimalaya/process" }
+# pimalaya-secret = { path = "/home/soywod/sourcehut/pimalaya/secret" }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 shellexpand = "2.1"
@@ -64,3 +69,8 @@ toml = "0.7.2"
 unicode-width = "0.1"
 url = "2.2"
 uuid = { version = "0.8", features = ["v4"] }
+
+[target.'cfg(target_env = "musl")'.dependencies]
+rusqlite = { version = "0.29", features = [] }
+[target.'cfg(not(target_env = "musl"))'.dependencies]
+rusqlite = { version = "0.29", features = ["bundled"] }
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index aff8cc2..3ccec48 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,11 +1,4 @@
 [toolchain]
 channel = "stable"
 profile = "default"
-components = [
-  "cargo",
-  "clippy",
-  "rust-analyzer",
-  "rust-std",
-  "rustc",
-  "rustfmt",
-]
+components = [ "rust-src", "rust-analyzer" ]
diff --git a/src/cache/id_mapper.rs b/src/cache/id_mapper.rs
new file mode 100644
index 0000000..4e5e251
--- /dev/null
+++ b/src/cache/id_mapper.rs
@@ -0,0 +1,187 @@
+use anyhow::{anyhow, Context, Result};
+use log::{debug, trace};
+#[cfg(feature = "imap-backend")]
+use pimalaya_email::ImapBackend;
+#[cfg(feature = "notmuch-backend")]
+use pimalaya_email::NotmuchBackend;
+use pimalaya_email::{Backend, MaildirBackend};
+use std::path::{Path, PathBuf};
+
+const ID_MAPPER_DB_FILE_NAME: &str = ".id-mapper.sqlite";
+
+#[derive(Debug)]
+pub enum IdMapper {
+    Dummy,
+    Mapper(String, rusqlite::Connection),
+}
+
+impl IdMapper {
+    fn find_closest_db_path<D>(dir: D) -> PathBuf
+    where
+        D: AsRef<Path>,
+    {
+        let mut db_path = dir.as_ref().join(ID_MAPPER_DB_FILE_NAME);
+        let mut db_parent_dir = dir.as_ref().parent();
+
+        while !db_path.is_file() {
+            match db_parent_dir {
+                Some(dir) => {
+                    db_path = dir.join(ID_MAPPER_DB_FILE_NAME);
+                    db_parent_dir = dir.parent();
+                }
+                None => {
+                    db_path = dir.as_ref().join(ID_MAPPER_DB_FILE_NAME);
+                    break;
+                }
+            }
+        }
+
+        db_path
+    }
+
+    pub fn new(backend: &dyn Backend, account: &str, folder: &str) -> Result<Self> {
+        let mut db_path = PathBuf::default();
+
+        if let Some(backend) = backend.as_any().downcast_ref::<MaildirBackend>() {
+            db_path = Self::find_closest_db_path(&backend.path());
+        }
+
+        #[cfg(feature = "imap-backend")]
+        if backend.as_any().is::<ImapBackend>() {
+            return Ok(Self::Dummy);
+        }
+
+        #[cfg(feature = "notmuch-backend")]
+        if let Some(backend) = backend.as_any().downcast_ref::<NotmuchBackend>() {
+            db_path = Self::find_closest_db_path(&backend.path());
+        }
+
+        let digest = md5::compute(account.to_string() + folder);
+        let table = format!("id_mapper_{digest:x}");
+        debug!("creating id mapper table {table} at {db_path:?}…");
+
+        let conn = rusqlite::Connection::open(&db_path)
+            .with_context(|| format!("cannot open id mapper database at {db_path:?}"))?;
+
+        let query = format!(
+            "CREATE TABLE IF NOT EXISTS {table} (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                internal_id TEXT UNIQUE
+            )",
+        );
+        trace!("create table query: {query:#?}");
+
+        conn.execute(&query, [])
+            .context("cannot create id mapper table")?;
+
+        Ok(Self::Mapper(table, conn))
+    }
+
+    pub fn create_alias<I>(&self, id: I) -> Result<String>
+    where
+        I: AsRef<str>,
+    {
+        let id = id.as_ref();
+        match self {
+            Self::Dummy => Ok(id.to_owned()),
+            Self::Mapper(table, conn) => {
+                debug!("creating alias for id {id}…");
+
+                let query = format!("INSERT OR IGNORE INTO {} (internal_id) VALUES (?)", table);
+                trace!("insert query: {query:#?}");
+
+                conn.execute(&query, [id])
+                    .with_context(|| format!("cannot create id alias for id {id}"))?;
+
+                let alias = conn.last_insert_rowid().to_string();
+                debug!("created alias {alias} for id {id}");
+
+                Ok(alias)
+            }
+        }
+    }
+
+    pub fn get_or_create_alias<I>(&self, id: I) -> Result<String>
+    where
+        I: AsRef<str>,
+    {
+        let id = id.as_ref();
+        match self {
+            Self::Dummy => Ok(id.to_owned()),
+            Self::Mapper(table, conn) => {
+                debug!("getting alias for id {id}…");
+
+                let query = format!("SELECT id FROM {} WHERE internal_id = ?", table);
+                trace!("select query: {query:#?}");
+
+                let mut stmt = conn
+                    .prepare(&query)
+                    .with_context(|| format!("cannot get alias for id {id}"))?;
+                let aliases: Vec<i64> = stmt
+                    .query_map([id], |row| row.get(0))
+                    .with_context(|| format!("cannot get alias for id {id}"))?
+                    .collect::<rusqlite::Result<_>>()
+                    .with_context(|| format!("cannot get alias for id {id}"))?;
+                let alias = match aliases.first() {
+                    Some(alias) => {
+                        debug!("found alias {alias} for id {id}");
+                        alias.to_string()
+                    }
+                    None => {
+                        debug!("alias not found, creating it…");
+                        self.create_alias(id)?
+                    }
+                };
+
+                Ok(alias)
+            }
+        }
+    }
+
+    pub fn get_id<A>(&self, alias: A) -> Result<String>
+    where
+        A: AsRef<str>,
+    {
+        let alias = alias.as_ref();
+        let alias = alias
+            .parse::<i64>()
+            .context(format!("cannot parse id mapper alias {alias}"))?;
+
+        match self {
+            Self::Dummy => Ok(alias.to_string()),
+            Self::Mapper(table, conn) => {
+                debug!("getting id from alias {alias}…");
+
+                let query = format!("SELECT internal_id FROM {} WHERE id = ?", table);
+                trace!("select query: {query:#?}");
+
+                let mut stmt = conn
+                    .prepare(&query)
+                    .with_context(|| format!("cannot get id from alias {alias}"))?;
+                let ids: Vec<String> = stmt
+                    .query_map([alias], |row| row.get(0))
+                    .with_context(|| format!("cannot get id from alias {alias}"))?
+                    .collect::<rusqlite::Result<_>>()
+                    .with_context(|| format!("cannot get id from alias {alias}"))?;
+                let id = ids
+                    .first()
+                    .ok_or_else(|| anyhow!("cannot get id from alias {alias}"))?
+                    .to_owned();
+                debug!("found id {id} from alias {alias}");
+
+                Ok(id)
+            }
+        }
+    }
+
+    pub fn get_ids<A, I>(&self, aliases: I) -> Result<Vec<String>>
+    where
+        A: AsRef<str>,
+        I: IntoIterator<Item = A>,
+    {
+        aliases
+            .into_iter()
+            .map(|alias| self.get_id(alias))
+            .collect()
+    }
+}
diff --git a/src/cache/mod.rs b/src/cache/mod.rs
index 6e10f4a..2dae5fe 100644
--- a/src/cache/mod.rs
+++ b/src/cache/mod.rs
@@ -1 +1,4 @@
 pub mod args;
+mod id_mapper;
+
+pub use id_mapper::IdMapper;
diff --git a/src/domain/email/handlers.rs b/src/domain/email/handlers.rs
index 6ddca41..13f4e10 100644
--- a/src/domain/email/handlers.rs
+++ b/src/domain/email/handlers.rs
@@ -14,17 +14,20 @@ use uuid::Uuid;
 use crate::{
     printer::{PrintTableOpts, Printer},
     ui::editor,
-    Envelopes,
+    Envelopes, IdMapper,
 };
 
-pub fn attachments<P: Printer, B: Backend + ?Sized>(
+pub fn attachments<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     ids: Vec<&str>,
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     let emails = backend.get_emails(&folder, ids.clone())?;
     let mut index = 0;
 
@@ -71,45 +74,54 @@ pub fn attachments<P: Printer, B: Backend + ?Sized>(
     }
 }
 
-pub fn copy<P: Printer, B: Backend + ?Sized>(
+pub fn copy<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     from_folder: &str,
     to_folder: &str,
     ids: Vec<&str>,
 ) -> Result<()> {
     let from_folder = config.folder_alias(from_folder)?;
     let to_folder = config.folder_alias(to_folder)?;
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     backend.copy_emails(&from_folder, &to_folder, ids)?;
     printer.print("Email(s) successfully copied!")
 }
 
-pub fn delete<P: Printer, B: Backend + ?Sized>(
+pub fn delete<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     ids: Vec<&str>,
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     backend.delete_emails(&folder, ids)?;
     printer.print("Email(s) successfully deleted!")
 }
 
-pub fn forward<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn forward<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     folder: &str,
     id: &str,
     headers: Option<Vec<&str>>,
     body: Option<&str>,
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
+    let ids = id_mapper.get_ids([id])?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     let tpl = backend
-        .get_emails(&folder, vec![id])?
+        .get_emails(&folder, ids)?
         .first()
         .ok_or_else(|| anyhow!("cannot find email {}", id))?
         .to_forward_tpl_builder(config)?
@@ -121,10 +133,11 @@ pub fn forward<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
     Ok(())
 }
 
-pub fn list<P: Printer, B: Backend + ?Sized>(
+pub fn list<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     max_width: Option<usize>,
     page_size: Option<usize>,
@@ -133,8 +146,11 @@ pub fn list<P: Printer, B: Backend + ?Sized>(
     let folder = config.folder_alias(folder)?;
     let page_size = page_size.unwrap_or(config.email_listing_page_size());
     debug!("page size: {}", page_size);
-    let envelopes: Envelopes = backend.list_envelopes(&folder, page_size, page)?.into();
+
+    let mut envelopes: Envelopes = backend.list_envelopes(&folder, page_size, page)?.into();
+    envelopes.remap_ids(id_mapper)?;
     trace!("envelopes: {:?}", envelopes);
+
     printer.print_table(
         Box::new(envelopes),
         PrintTableOpts {
@@ -147,11 +163,11 @@ pub fn list<P: Printer, B: Backend + ?Sized>(
 /// Parses and edits a message from a [mailto] URL string.
 ///
 /// [mailto]: https://en.wikipedia.org/wiki/Mailto
-pub fn mailto<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn mailto<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     url: &Url,
 ) -> Result<()> {
     let mut tpl = TplBuilder::default().to(url.path());
@@ -169,24 +185,28 @@ pub fn mailto<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
     editor::edit_tpl_with_editor(config, printer, backend, sender, tpl.build())
 }
 
-pub fn move_<P: Printer, B: Backend + ?Sized>(
+pub fn move_<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     from_folder: &str,
     to_folder: &str,
     ids: Vec<&str>,
 ) -> Result<()> {
     let from_folder = config.folder_alias(from_folder)?;
     let to_folder = config.folder_alias(to_folder)?;
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     backend.move_emails(&from_folder, &to_folder, ids)?;
     printer.print("Email(s) successfully moved!")
 }
 
-pub fn read<P: Printer, B: Backend + ?Sized>(
+pub fn read<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     ids: Vec<&str>,
     text_mime: &str,
@@ -195,6 +215,8 @@ pub fn read<P: Printer, B: Backend + ?Sized>(
     headers: Vec<&str>,
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     let emails = backend.get_emails(&folder, ids)?;
 
     let mut glue = "";
@@ -230,11 +252,12 @@ pub fn read<P: Printer, B: Backend + ?Sized>(
     printer.print(bodies)
 }
 
-pub fn reply<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn reply<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     folder: &str,
     id: &str,
     all: bool,
@@ -242,8 +265,10 @@ pub fn reply<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
     body: Option<&str>,
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
+    let ids = id_mapper.get_ids([id])?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     let tpl = backend
-        .get_emails(&folder, vec![id])?
+        .get_emails(&folder, ids)?
         .first()
         .ok_or_else(|| anyhow!("cannot find email {}", id))?
         .to_reply_tpl_builder(config, all)?
@@ -256,10 +281,11 @@ pub fn reply<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
     Ok(())
 }
 
-pub fn save<P: Printer, B: Backend + ?Sized>(
+pub fn save<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     raw_email: String,
 ) -> Result<()> {
@@ -276,14 +302,18 @@ pub fn save<P: Printer, B: Backend + ?Sized>(
             .collect::<Vec<String>>()
             .join("\r\n")
     };
-    backend.add_email(&folder, raw_email.as_bytes(), &Flags::default())?;
+
+    let id = backend.add_email(&folder, raw_email.as_bytes(), &Flags::default())?;
+    id_mapper.create_alias(id)?;
+
     Ok(())
 }
 
-pub fn search<P: Printer, B: Backend + ?Sized>(
+pub fn search<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     query: String,
     max_width: Option<usize>,
@@ -292,9 +322,10 @@ pub fn search<P: Printer, B: Backend + ?Sized>(
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
     let page_size = page_size.unwrap_or(config.email_listing_page_size());
-    let envelopes: Envelopes = backend
+    let mut envelopes: Envelopes = backend
         .search_envelopes(&folder, &query, "", page_size, page)?
         .into();
+    envelopes.remap_ids(id_mapper)?;
     let opts = PrintTableOpts {
         format: &config.email_reading_format,
         max_width,
@@ -303,10 +334,11 @@ pub fn search<P: Printer, B: Backend + ?Sized>(
     printer.print_table(Box::new(envelopes), opts)
 }
 
-pub fn sort<P: Printer, B: Backend + ?Sized>(
+pub fn sort<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     sort: String,
     query: String,
@@ -316,9 +348,10 @@ pub fn sort<P: Printer, B: Backend + ?Sized>(
 ) -> Result<()> {
     let folder = config.folder_alias(folder)?;
     let page_size = page_size.unwrap_or(config.email_listing_page_size());
-    let envelopes: Envelopes = backend
+    let mut envelopes: Envelopes = backend
         .search_envelopes(&folder, &query, &sort, page_size, page)?
         .into();
+    envelopes.remap_ids(id_mapper)?;
     let opts = PrintTableOpts {
         format: &config.email_reading_format,
         max_width,
@@ -327,11 +360,11 @@ pub fn sort<P: Printer, B: Backend + ?Sized>(
     printer.print_table(Box::new(envelopes), opts)
 }
 
-pub fn send<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn send<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     raw_email: String,
 ) -> Result<()> {
     let folder = config.sent_folder_alias()?;
@@ -357,11 +390,11 @@ pub fn send<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
     Ok(())
 }
 
-pub fn write<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn write<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     headers: Option<Vec<&str>>,
     body: Option<&str>,
 ) -> Result<()> {
diff --git a/src/domain/envelope/envelopes.rs b/src/domain/envelope/envelopes.rs
index 3efe2d3..f3352e0 100644
--- a/src/domain/envelope/envelopes.rs
+++ b/src/domain/envelope/envelopes.rs
@@ -1,18 +1,26 @@
-use std::ops;
-
 use anyhow::Result;
 use serde::Serialize;
+use std::ops;
 
 use crate::{
     printer::{PrintTable, PrintTableOpts, WriteColor},
     ui::Table,
-    Envelope,
+    Envelope, IdMapper,
 };
 
 /// Represents the list of envelopes.
 #[derive(Clone, Debug, Default, Serialize)]
 pub struct Envelopes(Vec<Envelope>);
 
+impl Envelopes {
+    pub fn remap_ids(&mut self, id_mapper: &IdMapper) -> Result<()> {
+        for envelope in &mut self.0 {
+            envelope.id = id_mapper.get_or_create_alias(&envelope.id)?;
+        }
+        Ok(())
+    }
+}
+
 impl ops::Deref for Envelopes {
     type Target = Vec<Envelope>;
 
diff --git a/src/domain/flag/handlers.rs b/src/domain/flag/handlers.rs
index 0e184f7..7381b69 100644
--- a/src/domain/flag/handlers.rs
+++ b/src/domain/flag/handlers.rs
@@ -1,37 +1,46 @@
 use anyhow::Result;
 use pimalaya_email::{Backend, Flags};
 
-use crate::printer::Printer;
+use crate::{printer::Printer, IdMapper};
 
-pub fn add<P: Printer, B: Backend + ?Sized>(
+pub fn add<P: Printer>(
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     ids: Vec<&str>,
     flags: &Flags,
 ) -> Result<()> {
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     backend.add_flags(folder, ids, flags)?;
     printer.print("Flag(s) successfully added!")
 }
 
-pub fn set<P: Printer, B: Backend + ?Sized>(
+pub fn set<P: Printer>(
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     ids: Vec<&str>,
     flags: &Flags,
 ) -> Result<()> {
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     backend.set_flags(folder, ids, flags)?;
     printer.print("Flag(s) successfully set!")
 }
 
-pub fn remove<P: Printer, B: Backend + ?Sized>(
+pub fn remove<P: Printer>(
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     ids: Vec<&str>,
     flags: &Flags,
 ) -> Result<()> {
+    let ids = id_mapper.get_ids(ids)?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     backend.remove_flags(folder, ids, flags)?;
     printer.print("Flag(s) successfully removed!")
 }
diff --git a/src/domain/folder/handlers.rs b/src/domain/folder/handlers.rs
index b433ddc..598df98 100644
--- a/src/domain/folder/handlers.rs
+++ b/src/domain/folder/handlers.rs
@@ -12,19 +12,15 @@ use crate::{
     Folders,
 };
 
-pub fn expunge<P: Printer, B: Backend + ?Sized>(
-    printer: &mut P,
-    backend: &mut B,
-    folder: &str,
-) -> Result<()> {
+pub fn expunge<P: Printer>(printer: &mut P, backend: &mut dyn Backend, folder: &str) -> Result<()> {
     backend.expunge_folder(folder)?;
     printer.print(format!("Folder {folder} successfully expunged!"))
 }
 
-pub fn list<P: Printer, B: Backend + ?Sized>(
+pub fn list<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    backend: &mut dyn Backend,
     max_width: Option<usize>,
 ) -> Result<()> {
     let folders: Folders = backend.list_folders()?.into();
@@ -38,20 +34,12 @@ pub fn list<P: Printer, B: Backend + ?Sized>(
     )
 }
 
-pub fn create<P: Printer, B: Backend + ?Sized>(
-    printer: &mut P,
-    backend: &mut B,
-    folder: &str,
-) -> Result<()> {
+pub fn create<P: Printer>(printer: &mut P, backend: &mut dyn Backend, folder: &str) -> Result<()> {
     backend.add_folder(folder)?;
     printer.print("Folder successfully created!")
 }
 
-pub fn delete<P: Printer, B: Backend + ?Sized>(
-    printer: &mut P,
-    backend: &mut B,
-    folder: &str,
-) -> Result<()> {
+pub fn delete<P: Printer>(printer: &mut P, backend: &mut dyn Backend, folder: &str) -> Result<()> {
     if let Some(false) | None = Confirm::new()
         .with_prompt(format!("Confirm deletion of folder {folder}?"))
         .default(false)
@@ -176,9 +164,6 @@ mod tests {
             fn get_envelope(&self, _: &str, _: &str) -> backend::Result<Envelope> {
                 unimplemented!();
             }
-            fn get_envelope_internal(&self, _: &str, _: &str) -> backend::Result<Envelope> {
-                unimplemented!();
-            }
             fn list_envelopes(&self, _: &str, _: usize, _: usize) -> backend::Result<Envelopes> {
                 unimplemented!()
             }
@@ -195,60 +180,31 @@ mod tests {
             fn add_email(&self, _: &str, _: &[u8], _: &Flags) -> backend::Result<String> {
                 unimplemented!()
             }
-            fn add_email_internal(&self, _: &str, _: &[u8], _: &Flags) -> backend::Result<String> {
-                unimplemented!()
-            }
             fn get_emails(&self, _: &str, _: Vec<&str>) -> backend::Result<Emails> {
                 unimplemented!()
             }
             fn preview_emails(&self, _: &str, _: Vec<&str>) -> backend::Result<Emails> {
                 unimplemented!()
             }
-            fn get_emails_internal(&self, _: &str, _: Vec<&str>) -> backend::Result<Emails> {
-                unimplemented!()
-            }
             fn copy_emails(&self, _: &str, _: &str, _: Vec<&str>) -> backend::Result<()> {
                 unimplemented!()
             }
-            fn copy_emails_internal(&self, _: &str, _: &str, _: Vec<&str>) -> backend::Result<()> {
-                unimplemented!()
-            }
             fn move_emails(&self, _: &str, _: &str, _: Vec<&str>) -> backend::Result<()> {
                 unimplemented!()
             }
-            fn move_emails_internal(&self, _: &str, _: &str, _: Vec<&str>) -> backend::Result<()> {
-                unimplemented!()
-            }
             fn delete_emails(&self, _: &str, _: Vec<&str>) -> backend::Result<()> {
                 unimplemented!()
             }
-            fn delete_emails_internal(&self, _: &str, _: Vec<&str>) -> backend::Result<()> {
-                unimplemented!()
-            }
             fn add_flags(&self, _: &str, _: Vec<&str>, _: &Flags) -> backend::Result<()> {
                 unimplemented!()
             }
-            fn add_flags_internal(&self, _: &str, _: Vec<&str>, _: &Flags) -> backend::Result<()> {
-                unimplemented!()
-            }
             fn set_flags(&self, _: &str, _: Vec<&str>, _: &Flags) -> backend::Result<()> {
                 unimplemented!()
             }
-            fn set_flags_internal(&self, _: &str, _: Vec<&str>, _: &Flags) -> backend::Result<()> {
-                unimplemented!()
-            }
             fn remove_flags(&self, _: &str, _: Vec<&str>, _: &Flags) -> backend::Result<()> {
                 unimplemented!()
             }
-            fn remove_flags_internal(
-                &self,
-                _: &str,
-                _: Vec<&str>,
-                _: &Flags,
-            ) -> backend::Result<()> {
-                unimplemented!()
-            }
-            fn as_any(&'static self) -> &(dyn Any) {
+            fn as_any(&self) -> &(dyn Any) {
                 self
             }
         }
diff --git a/src/domain/tpl/handlers.rs b/src/domain/tpl/handlers.rs
index 9f09b3b..d74561e 100644
--- a/src/domain/tpl/handlers.rs
+++ b/src/domain/tpl/handlers.rs
@@ -3,19 +3,22 @@ use atty::Stream;
 use pimalaya_email::{AccountConfig, Backend, CompilerBuilder, Email, Flags, Sender, Tpl};
 use std::io::{stdin, BufRead};
 
-use crate::printer::Printer;
+use crate::{printer::Printer, IdMapper};
 
-pub fn forward<P: Printer, B: Backend + ?Sized>(
+pub fn forward<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     id: &str,
     headers: Option<Vec<&str>>,
     body: Option<&str>,
 ) -> Result<()> {
+    let ids = id_mapper.get_ids([id])?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     let tpl = backend
-        .get_emails(folder, vec![id])?
+        .get_emails(folder, ids)?
         .first()
         .ok_or_else(|| anyhow!("cannot find email {}", id))?
         .to_forward_tpl_builder(config)?
@@ -26,18 +29,21 @@ pub fn forward<P: Printer, B: Backend + ?Sized>(
     printer.print(<Tpl as Into<String>>::into(tpl))
 }
 
-pub fn reply<P: Printer, B: Backend + ?Sized>(
+pub fn reply<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     id: &str,
     all: bool,
     headers: Option<Vec<&str>>,
     body: Option<&str>,
 ) -> Result<()> {
+    let ids = id_mapper.get_ids([id])?;
+    let ids = ids.iter().map(String::as_str).collect::<Vec<_>>();
     let tpl = backend
-        .get_emails(folder, vec![id])?
+        .get_emails(folder, ids)?
         .first()
         .ok_or_else(|| anyhow!("cannot find email {}", id))?
         .to_reply_tpl_builder(config, all)?
@@ -48,10 +54,11 @@ pub fn reply<P: Printer, B: Backend + ?Sized>(
     printer.print(<Tpl as Into<String>>::into(tpl))
 }
 
-pub fn save<P: Printer, B: Backend + ?Sized>(
+pub fn save<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
+    id_mapper: &IdMapper,
+    backend: &mut dyn Backend,
     folder: &str,
     tpl: String,
 ) -> Result<()> {
@@ -71,15 +78,17 @@ pub fn save<P: Printer, B: Backend + ?Sized>(
             .some_pgp_encrypt_cmd(config.email_writing_encrypt_cmd.as_ref()),
     )?;
 
-    backend.add_email(folder, &email, &Flags::default())?;
+    let id = backend.add_email(folder, &email, &Flags::default())?;
+    id_mapper.create_alias(id)?;
+
     printer.print("Template successfully saved!")
 }
 
-pub fn send<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn send<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     folder: &str,
     tpl: String,
 ) -> Result<()> {
@@ -114,6 +123,5 @@ pub fn write<'a, P: Printer>(
         .set_some_raw_headers(headers)
         .some_text_plain_part(body)
         .build();
-
     printer.print(<Tpl as Into<String>>::into(tpl))
 }
diff --git a/src/lib.rs b/src/lib.rs
index 4ba6146..962bab0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,4 +7,5 @@ pub mod output;
 pub mod printer;
 pub mod ui;
 
+pub use cache::*;
 pub use domain::*;
diff --git a/src/main.rs b/src/main.rs
index f6fff46..3553aca 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,9 @@
 use anyhow::{anyhow, Context, Result};
 use clap::Command;
-use std::{borrow::Cow, env};
+use pimalaya_email::{
+    BackendBuilder, BackendConfig, ImapBackend, SenderBuilder, DEFAULT_INBOX_FOLDER,
+};
+use std::env;
 use url::Url;
 
 use himalaya::{
@@ -8,10 +11,7 @@ use himalaya::{
     config::{self, DeserializedConfig},
     email, flag, folder, man, output,
     printer::StdoutPrinter,
-    tpl,
-};
-use pimalaya_email::{
-    BackendBuilder, BackendConfig, ImapBackend, SenderBuilder, DEFAULT_INBOX_FOLDER,
+    tpl, IdMapper,
 };
 
 #[cfg(feature = "imap-backend")]
@@ -52,7 +52,8 @@ fn main() -> Result<()> {
         let url = Url::parse(&raw_args[1])?;
         let config = DeserializedConfig::from_opt_path(None)?;
         let (account_config, backend_config) = config.to_configs(None)?;
-        let mut backend = BackendBuilder::new().build(&account_config, &backend_config)?;
+        let mut backend =
+            BackendBuilder::new().build(account_config.clone(), backend_config.clone())?;
         let mut sender = SenderBuilder::build(&account_config)?;
         let mut printer = StdoutPrinter::default();
 
@@ -99,13 +100,11 @@ fn main() -> Result<()> {
         // recreating an instance.
         match imap::args::matches(&m)? {
             Some(imap::args::Cmd::Notify(keepalive)) => {
-                let imap =
-                    ImapBackend::new(Cow::Borrowed(&account_config), Cow::Borrowed(&imap_config))?;
+                let imap = ImapBackend::new(account_config.clone(), imap_config.clone())?;
                 return imap::handlers::notify(&imap, &folder, keepalive);
             }
             Some(imap::args::Cmd::Watch(keepalive)) => {
-                let imap =
-                    ImapBackend::new(Cow::Borrowed(&account_config), Cow::Borrowed(&imap_config))?;
+                let imap = ImapBackend::new(account_config.clone(), imap_config.clone())?;
                 return imap::handlers::watch(&imap, &folder, keepalive);
             }
             _ => (),
@@ -126,7 +125,7 @@ fn main() -> Result<()> {
             let backend = BackendBuilder::new()
                 .sessions_pool_size(8)
                 .disable_cache(true)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             account::handlers::sync(
                 &account_config,
                 &mut printer,
@@ -152,13 +151,13 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder)?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             return folder::handlers::create(&mut printer, backend.as_mut(), &folder);
         }
         Some(folder::args::Cmd::List(max_width)) => {
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             return folder::handlers::list(
                 &account_config,
                 &mut printer,
@@ -170,7 +169,7 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             return folder::handlers::expunge(&mut printer, backend.as_mut(), &folder);
         }
         Some(folder::args::Cmd::Delete) => {
@@ -180,7 +179,7 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder)?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             return folder::handlers::delete(&mut printer, backend.as_mut(), &folder);
         }
         _ => (),
@@ -192,10 +191,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::attachments(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 ids,
@@ -205,10 +206,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::copy(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 to_folder,
@@ -219,10 +222,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::delete(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 ids,
@@ -232,10 +237,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::forward(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 sender.as_mut(),
                 &folder,
@@ -248,10 +255,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::list(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 max_width,
@@ -263,10 +272,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::move_(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 to_folder,
@@ -277,10 +288,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::read(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 ids,
@@ -294,10 +307,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::reply(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 sender.as_mut(),
                 &folder,
@@ -311,10 +326,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::save(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 raw_email,
@@ -324,10 +341,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::search(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 query,
@@ -340,10 +359,12 @@ fn main() -> Result<()> {
             let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
+            let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
             return email::handlers::sort(
                 &account_config,
                 &mut printer,
+                &id_mapper,
                 backend.as_mut(),
                 &folder,
                 criteria,
@@ -356,7 +377,7 @@ fn main() -> Result<()> {
         Some(email::args::Cmd::Send(raw_email)) => {
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             return email::handlers::send(
                 &account_config,
                 &mut printer,
@@ -370,22 +391,46 @@ fn main() -> Result<()> {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
-                return flag::handlers::set(&mut printer, backend.as_mut(), &folder, ids, flags);
+                    .build(account_config.clone(), backend_config.clone())?;
+                let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
+                return flag::handlers::set(
+                    &mut printer,
+                    &id_mapper,
+                    backend.as_mut(),
+                    &folder,
+                    ids,
+                    flags,
+                );
             }
             Some(flag::args::Cmd::Add(ids, ref flags)) => {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
-                return flag::handlers::add(&mut printer, backend.as_mut(), &folder, ids, flags);
+                    .build(account_config.clone(), backend_config.clone())?;
+                let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
+                return flag::handlers::add(
+                    &mut printer,
+                    &id_mapper,
+                    backend.as_mut(),
+                    &folder,
+                    ids,
+                    flags,
+                );
             }
             Some(flag::args::Cmd::Remove(ids, ref flags)) => {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
-                return flag::handlers::remove(&mut printer, backend.as_mut(), &folder, ids, flags);
+                    .build(account_config.clone(), backend_config.clone())?;
+                let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
+                return flag::handlers::remove(
+                    &mut printer,
+                    &id_mapper,
+                    backend.as_mut(),
+                    &folder,
+                    ids,
+                    flags,
+                );
             }
             _ => (),
         },
@@ -394,10 +439,12 @@ fn main() -> Result<()> {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
+                    .build(account_config.clone(), backend_config.clone())?;
+                let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
                 return tpl::handlers::forward(
                     &account_config,
                     &mut printer,
+                    &id_mapper,
                     backend.as_mut(),
                     &folder,
                     id,
@@ -412,10 +459,12 @@ fn main() -> Result<()> {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
+                    .build(account_config.clone(), backend_config.clone())?;
+                let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
                 return tpl::handlers::reply(
                     &account_config,
                     &mut printer,
+                    &id_mapper,
                     backend.as_mut(),
                     &folder,
                     id,
@@ -428,10 +477,12 @@ fn main() -> Result<()> {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
+                    .build(account_config.clone(), backend_config.clone())?;
+                let id_mapper = IdMapper::new(backend.as_ref(), &account_config.name, &folder)?;
                 return tpl::handlers::save(
                     &account_config,
                     &mut printer,
+                    &id_mapper,
                     backend.as_mut(),
                     &folder,
                     tpl,
@@ -441,7 +492,7 @@ fn main() -> Result<()> {
                 let folder = account_config.folder_alias(folder.unwrap_or(DEFAULT_INBOX_FOLDER))?;
                 let mut backend = BackendBuilder::new()
                     .disable_cache(disable_cache)
-                    .build(&account_config, &backend_config)?;
+                    .build(account_config.clone(), backend_config.clone())?;
                 return tpl::handlers::send(
                     &account_config,
                     &mut printer,
@@ -456,7 +507,7 @@ fn main() -> Result<()> {
         Some(email::args::Cmd::Write(headers, body)) => {
             let mut backend = BackendBuilder::new()
                 .disable_cache(disable_cache)
-                .build(&account_config, &backend_config)?;
+                .build(account_config.clone(), backend_config.clone())?;
             return email::handlers::write(
                 &account_config,
                 &mut printer,
diff --git a/src/ui/editor.rs b/src/ui/editor.rs
index 87ca7b1..795332a 100644
--- a/src/ui/editor.rs
+++ b/src/ui/editor.rs
@@ -37,11 +37,11 @@ pub fn open_with_local_draft() -> Result<Tpl> {
     open_with_tpl(Tpl::from(content))
 }
 
-pub fn edit_tpl_with_editor<P: Printer, B: Backend + ?Sized, S: Sender + ?Sized>(
+pub fn edit_tpl_with_editor<P: Printer>(
     config: &AccountConfig,
     printer: &mut P,
-    backend: &mut B,
-    sender: &mut S,
+    backend: &mut dyn Backend,
+    sender: &mut dyn Sender,
     mut tpl: Tpl,
 ) -> Result<()> {
     let draft = local_draft_path();