diff --git a/app/api/views/auth.py b/app/api/views/auth.py
index b817bda1..5b1ce087 100644
--- a/app/api/views/auth.py
+++ b/app/api/views/auth.py
@@ -12,7 +12,7 @@ from app.api.base import api_bp
 from app.config import FLASK_SECRET, DISABLE_REGISTRATION
 from app.dashboard.views.setting import send_reset_password_email
 from app.email_utils import (
-    email_domain_can_be_used_as_mailbox,
+    email_can_be_used_as_mailbox,
     personal_email_already_used,
     send_email,
     render,
@@ -89,9 +89,7 @@ def auth_register():
 
     if DISABLE_REGISTRATION:
         return jsonify(error="registration is closed"), 400
-    if not email_domain_can_be_used_as_mailbox(email) or personal_email_already_used(
-        email
-    ):
+    if not email_can_be_used_as_mailbox(email) or personal_email_already_used(email):
         return jsonify(error=f"cannot use {email} as personal inbox"), 400
 
     if not password or len(password) < 8:
@@ -249,9 +247,9 @@ def auth_facebook():
     if not user:
         if DISABLE_REGISTRATION:
             return jsonify(error="registration is closed"), 400
-        if not email_domain_can_be_used_as_mailbox(
+        if not email_can_be_used_as_mailbox(email) or personal_email_already_used(
             email
-        ) or personal_email_already_used(email):
+        ):
             return jsonify(error=f"cannot use {email} as personal inbox"), 400
 
         LOG.d("create facebook user with %s", user_info)
@@ -302,9 +300,9 @@ def auth_google():
     if not user:
         if DISABLE_REGISTRATION:
             return jsonify(error="registration is closed"), 400
-        if not email_domain_can_be_used_as_mailbox(
+        if not email_can_be_used_as_mailbox(email) or personal_email_already_used(
             email
-        ) or personal_email_already_used(email):
+        ):
             return jsonify(error=f"cannot use {email} as personal inbox"), 400
 
         LOG.d("create Google user with %s", user_info)
diff --git a/app/api/views/mailbox.py b/app/api/views/mailbox.py
index 517148ac..b70085df 100644
--- a/app/api/views/mailbox.py
+++ b/app/api/views/mailbox.py
@@ -9,7 +9,7 @@ from app.dashboard.views.mailbox import send_verification_email
 from app.dashboard.views.mailbox_detail import verify_mailbox_change
 from app.email_utils import (
     mailbox_already_used,
-    email_domain_can_be_used_as_mailbox,
+    email_can_be_used_as_mailbox,
 )
 from app.extensions import db
 from app.models import Mailbox
@@ -34,7 +34,7 @@ def create_mailbox():
 
     if mailbox_already_used(mailbox_email, user):
         return jsonify(error=f"{mailbox_email} already used"), 400
-    elif not email_domain_can_be_used_as_mailbox(mailbox_email):
+    elif not email_can_be_used_as_mailbox(mailbox_email):
         return (
             jsonify(
                 error=f"{mailbox_email} cannot be used. Please note a mailbox cannot "
@@ -118,7 +118,7 @@ def update_mailbox(mailbox_id):
 
         if mailbox_already_used(new_email, user):
             return jsonify(error=f"{new_email} already used"), 400
-        elif not email_domain_can_be_used_as_mailbox(new_email):
+        elif not email_can_be_used_as_mailbox(new_email):
             return (
                 jsonify(
                     error=f"{new_email} cannot be used. Please note a mailbox cannot "
diff --git a/app/auth/views/register.py b/app/auth/views/register.py
index e25ab3ec..70dcb5f8 100644
--- a/app/auth/views/register.py
+++ b/app/auth/views/register.py
@@ -9,7 +9,7 @@ from app.auth.base import auth_bp
 from app.auth.views.login_utils import get_referral
 from app.config import URL, HCAPTCHA_SECRET, HCAPTCHA_SITEKEY
 from app.email_utils import (
-    email_domain_can_be_used_as_mailbox,
+    email_can_be_used_as_mailbox,
     personal_email_already_used,
 )
 from app.extensions import db
@@ -67,7 +67,7 @@ def register():
                 )
 
         email = form.email.data.strip().lower()
-        if not email_domain_can_be_used_as_mailbox(email):
+        if not email_can_be_used_as_mailbox(email):
             flash("You cannot use this email address as your personal inbox.", "error")
 
         else:
diff --git a/app/dashboard/views/mailbox.py b/app/dashboard/views/mailbox.py
index a14333fa..0edd2839 100644
--- a/app/dashboard/views/mailbox.py
+++ b/app/dashboard/views/mailbox.py
@@ -8,7 +8,7 @@ from wtforms.fields.html5 import EmailField
 from app.config import EMAIL_DOMAIN, ALIAS_DOMAINS, MAILBOX_SECRET, URL
 from app.dashboard.base import dashboard_bp
 from app.email_utils import (
-    email_domain_can_be_used_as_mailbox,
+    email_can_be_used_as_mailbox,
     mailbox_already_used,
     render,
     send_email,
@@ -88,7 +88,7 @@ def mailbox_route():
 
                 if mailbox_already_used(mailbox_email, current_user):
                     flash(f"{mailbox_email} already used", "error")
-                elif not email_domain_can_be_used_as_mailbox(mailbox_email):
+                elif not email_can_be_used_as_mailbox(mailbox_email):
                     flash(f"You cannot use {mailbox_email}.", "error")
                 else:
                     new_mailbox = Mailbox.create(
diff --git a/app/dashboard/views/mailbox_detail.py b/app/dashboard/views/mailbox_detail.py
index fc0a519d..1f422397 100644
--- a/app/dashboard/views/mailbox_detail.py
+++ b/app/dashboard/views/mailbox_detail.py
@@ -10,7 +10,7 @@ from wtforms.fields.html5 import EmailField
 from app.config import ENFORCE_SPF, MAILBOX_SECRET
 from app.config import URL
 from app.dashboard.base import dashboard_bp
-from app.email_utils import email_domain_can_be_used_as_mailbox
+from app.email_utils import email_can_be_used_as_mailbox
 from app.email_utils import mailbox_already_used, render, send_email
 from app.extensions import db
 from app.log import LOG
@@ -52,7 +52,7 @@ def mailbox_detail_route(mailbox_id):
                     email=new_email
                 ):
                     flash(f"Email {new_email} already used", "error")
-                elif not email_domain_can_be_used_as_mailbox(new_email):
+                elif not email_can_be_used_as_mailbox(new_email):
                     flash("You cannot use this email address as your mailbox", "error")
                 else:
                     mailbox.new_email = new_email
diff --git a/app/dashboard/views/setting.py b/app/dashboard/views/setting.py
index 2282285d..5b7730d3 100644
--- a/app/dashboard/views/setting.py
+++ b/app/dashboard/views/setting.py
@@ -22,7 +22,7 @@ from app import s3, email_utils
 from app.config import URL, FIRST_ALIAS_DOMAIN
 from app.dashboard.base import dashboard_bp
 from app.email_utils import (
-    email_domain_can_be_used_as_mailbox,
+    email_can_be_used_as_mailbox,
     personal_email_already_used,
 )
 from app.extensions import db
@@ -90,7 +90,7 @@ def setting():
                     ):
                         flash(f"Email {new_email} already used", "error")
                         new_email_valid = False
-                    elif not email_domain_can_be_used_as_mailbox(new_email):
+                    elif not email_can_be_used_as_mailbox(new_email):
                         flash(
                             "You cannot use this email address as your personal inbox.",
                             "error",