diff --git a/app/api/views/new_custom_alias.py b/app/api/views/new_custom_alias.py
index be188d0b..d04dd2b4 100644
--- a/app/api/views/new_custom_alias.py
+++ b/app/api/views/new_custom_alias.py
@@ -51,7 +51,7 @@ def new_custom_alias():
     note = data.get("note")
     alias_prefix = convert_to_id(alias_prefix)
 
-    if not verify_prefix_suffix(user, alias_prefix, alias_suffix, user_custom_domains):
+    if not verify_prefix_suffix(user, alias_prefix, alias_suffix):
         return jsonify(error="wrong alias prefix or suffix"), 400
 
     full_alias = alias_prefix + alias_suffix
diff --git a/app/dashboard/views/custom_alias.py b/app/dashboard/views/custom_alias.py
index 8e13b647..4523f2fb 100644
--- a/app/dashboard/views/custom_alias.py
+++ b/app/dashboard/views/custom_alias.py
@@ -71,9 +71,7 @@ def custom_alias():
             flash("Unknown error, refresh the page", "error")
             return redirect(url_for("dashboard.custom_alias"))
 
-        if verify_prefix_suffix(
-            current_user, alias_prefix, alias_suffix, user_custom_domains
-        ):
+        if verify_prefix_suffix(current_user, alias_prefix, alias_suffix):
             full_alias = alias_prefix + alias_suffix
 
             if Alias.get_by(email=full_alias) or DeletedAlias.get_by(email=full_alias):
@@ -110,11 +108,12 @@ def custom_alias():
     return render_template("dashboard/custom_alias.html", **locals())
 
 
-def verify_prefix_suffix(user, alias_prefix, alias_suffix, user_custom_domains) -> bool:
+def verify_prefix_suffix(user, alias_prefix, alias_suffix) -> bool:
     """verify if user could create an alias with the given prefix and suffix"""
     if not alias_prefix or not alias_suffix:  # should be caught on frontend
         return False
 
+    user_custom_domains = [cd.domain for cd in user.verified_custom_domains()]
     alias_prefix = alias_prefix.strip()
     alias_prefix = convert_to_id(alias_prefix)
 
diff --git a/app/oauth/views/authorize.py b/app/oauth/views/authorize.py
index 740b20bc..ee37a332 100644
--- a/app/oauth/views/authorize.py
+++ b/app/oauth/views/authorize.py
@@ -171,9 +171,7 @@ def authorize():
 
                 from app.dashboard.views.custom_alias import verify_prefix_suffix
 
-                if verify_prefix_suffix(
-                    current_user, alias_prefix, alias_suffix, user_custom_domains
-                ):
+                if verify_prefix_suffix(current_user, alias_prefix, alias_suffix):
                     full_alias = alias_prefix + alias_suffix
 
                     if Alias.get_by(email=full_alias) or DeletedAlias.get_by(
diff --git a/tests/dashboard/test_custom_alias.py b/tests/dashboard/test_custom_alias.py
index 7d0e2519..7245d385 100644
--- a/tests/dashboard/test_custom_alias.py
+++ b/tests/dashboard/test_custom_alias.py
@@ -1,9 +1,9 @@
 from flask import url_for
 
 from app.config import EMAIL_DOMAIN
-from app.dashboard.views.custom_alias import signer
+from app.dashboard.views.custom_alias import signer, verify_prefix_suffix
 from app.extensions import db
-from app.models import Mailbox
+from app.models import Mailbox, CustomDomain
 from app.utils import random_word
 from tests.utils import login
 
@@ -39,3 +39,17 @@ def test_not_show_unverified_mailbox(flask_client):
 
     assert "m1@example.com" in str(r.data)
     assert "m2@example.com" not in str(r.data)
+
+
+def test_verify_prefix_suffix(flask_client):
+    user = login(flask_client)
+    db.session.commit()
+
+    CustomDomain.create(user_id=user.id, domain="test.com", verified=True)
+
+    assert verify_prefix_suffix(user, "prefix", "@test.com")
+    assert not verify_prefix_suffix(user, "prefix", "@abcd.com")
+
+    word = random_word()
+    suffix = f".{word}@{EMAIL_DOMAIN}"
+    assert verify_prefix_suffix(user, "prefix", suffix)