diff --git a/cli/src/backends/backend.rs b/cli/src/backends/backend.rs
index d6cb7b4..92dc363 100644
--- a/cli/src/backends/backend.rs
+++ b/cli/src/backends/backend.rs
@@ -30,7 +30,7 @@ pub trait Backend<'a> {
         page_size: usize,
         page: usize,
     ) -> Result<Box<dyn Envelopes>>;
-    fn add_msg(&mut self, mbox: &str, msg: &[u8], flags: &str) -> Result<Box<dyn ToString>>;
+    fn add_msg(&mut self, mbox: &str, msg: &[u8], flags: &str) -> Result<String>;
     fn get_msg(&mut self, mbox: &str, id: &str) -> Result<Msg>;
     fn copy_msg(&mut self, mbox_src: &str, mbox_dst: &str, ids: &str) -> Result<()>;
     fn move_msg(&mut self, mbox_src: &str, mbox_dst: &str, ids: &str) -> Result<()>;
diff --git a/cli/src/backends/imap/imap_backend.rs b/cli/src/backends/imap/imap_backend.rs
index f54d066..76ed158 100644
--- a/cli/src/backends/imap/imap_backend.rs
+++ b/cli/src/backends/imap/imap_backend.rs
@@ -342,7 +342,7 @@ impl<'a> Backend<'a> for ImapBackend<'a> {
         Ok(Box::new(envelopes))
     }
 
-    fn add_msg(&mut self, mbox: &str, msg: &[u8], flags: &str) -> Result<Box<dyn ToString>> {
+    fn add_msg(&mut self, mbox: &str, msg: &[u8], flags: &str) -> Result<String> {
         let flags: ImapFlags = flags.into();
         self.sess()?
             .append(mbox, msg)
@@ -354,7 +354,7 @@ impl<'a> Backend<'a> for ImapBackend<'a> {
             .select(mbox)
             .context(format!("cannot select mailbox {:?}", mbox))?
             .exists;
-        Ok(Box::new(last_seq))
+        Ok(last_seq.to_string())
     }
 
     fn get_msg(&mut self, mbox: &str, seq: &str) -> Result<Msg> {
diff --git a/cli/src/backends/maildir/maildir_backend.rs b/cli/src/backends/maildir/maildir_backend.rs
index 1f6b61f..0acba73 100644
--- a/cli/src/backends/maildir/maildir_backend.rs
+++ b/cli/src/backends/maildir/maildir_backend.rs
@@ -215,7 +215,7 @@ impl<'a> Backend<'a> for MaildirBackend<'a> {
         ))
     }
 
-    fn add_msg(&mut self, dir: &str, msg: &[u8], flags: &str) -> Result<Box<dyn ToString>> {
+    fn add_msg(&mut self, dir: &str, msg: &[u8], flags: &str) -> Result<String> {
         info!(">> add maildir message");
         debug!("dir: {:?}", dir);
         debug!("flags: {:?}", flags);
@@ -246,7 +246,7 @@ impl<'a> Backend<'a> for MaildirBackend<'a> {
             })?;
 
         info!("<< add maildir message");
-        Ok(Box::new(hash))
+        Ok(hash)
     }
 
     fn get_msg(&mut self, dir: &str, short_hash: &str) -> Result<Msg> {
diff --git a/cli/src/backends/notmuch/notmuch_backend.rs b/cli/src/backends/notmuch/notmuch_backend.rs
index 03cbd26..8f71faf 100644
--- a/cli/src/backends/notmuch/notmuch_backend.rs
+++ b/cli/src/backends/notmuch/notmuch_backend.rs
@@ -197,7 +197,7 @@ impl<'a> Backend<'a> for NotmuchBackend<'a> {
         Ok(envelopes)
     }
 
-    fn add_msg(&mut self, _: &str, msg: &[u8], tags: &str) -> Result<Box<dyn ToString>> {
+    fn add_msg(&mut self, _: &str, msg: &[u8], tags: &str) -> Result<String> {
         info!(">> add notmuch envelopes");
         debug!("tags: {:?}", tags);
 
@@ -251,7 +251,7 @@ impl<'a> Backend<'a> for NotmuchBackend<'a> {
             .with_context(|| format!("cannot add flags to notmuch message {:?}", id))?;
 
         info!("<< add notmuch envelopes");
-        Ok(Box::new(hash))
+        Ok(hash)
     }
 
     fn get_msg(&mut self, _: &str, short_hash: &str) -> Result<Msg> {
diff --git a/cli/src/mbox/mbox_handlers.rs b/cli/src/mbox/mbox_handlers.rs
index f8f5c5e..b22a943 100644
--- a/cli/src/mbox/mbox_handlers.rs
+++ b/cli/src/mbox/mbox_handlers.rs
@@ -120,10 +120,12 @@ mod tests {
                         Mbox {
                             delim: "/".into(),
                             name: "INBOX".into(),
+                            desc: "desc".into(),
                         },
                         Mbox {
                             delim: "/".into(),
                             name: "Sent".into(),
+                            desc: "desc".into(),
                         },
                     ],
                 })
@@ -144,7 +146,7 @@ mod tests {
             ) -> Result<Box<dyn Envelopes>> {
                 unimplemented!()
             }
-            fn add_msg(&mut self, _: &str, _: &[u8], _: &str) -> Result<Box<dyn ToString>> {
+            fn add_msg(&mut self, _: &str, _: &[u8], _: &str) -> Result<String> {
                 unimplemented!()
             }
             fn get_msg(&mut self, _: &str, _: &str) -> Result<Msg> {
@@ -179,9 +181,9 @@ mod tests {
         assert_eq!(
             concat![
                 "\n",
-                "DELIM │NAME  │ATTRIBUTES                 \n",
-                "/     │INBOX │NoSelect                   \n",
-                "/     │Sent  │NoInferiors, HasNoChildren \n",
+                "DELIM │NAME  │DESC \n",
+                "/     │INBOX │desc \n",
+                "/     │Sent  │desc \n",
                 "\n"
             ],
             printer.writer.content