diff --git a/app/email_utils.py b/app/email_utils.py
index ddbfbaab..5ccc852f 100644
--- a/app/email_utils.py
+++ b/app/email_utils.py
@@ -1070,7 +1070,7 @@ def generate_reply_email(contact_email: str, alias: Alias) -> str:
         contact_email = contact_email.replace(".", "_")
         contact_email = convert_to_alphanumeric(contact_email)
 
-    reply_domain = alias.get_domain()
+    reply_domain = get_email_domain_part(alias.email)
     # not use while to avoid infinite loop
     for _ in range(1000):
         if include_sender_in_reverse_alias and contact_email:
diff --git a/app/models.py b/app/models.py
index 9cf2d845..7782d984 100644
--- a/app/models.py
+++ b/app/models.py
@@ -1593,10 +1593,6 @@ class Alias(Base, ModelMixin):
         else:
             return self.user.email
 
-    def get_domain(self) -> str:
-        splitPos = self.email.find("@")
-        return self.email[splitPos + 1 :]
-
     def __repr__(self):
         return f"<Alias {self.id} {self.email}>"
 
diff --git a/email_handler.py b/email_handler.py
index a00192d9..fbdb3f0e 100644
--- a/email_handler.py
+++ b/email_handler.py
@@ -1032,7 +1032,7 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
 
     alias = contact.alias
     alias_address: str = contact.alias.email
-    alias_domain = alias_address[alias_address.find("@") + 1 :]
+    alias_domain = get_email_domain_part(alias_address)
 
     # Sanity check: verify alias domain is managed by SimpleLogin
     # scenario: a user have removed a domain but due to a bug, the aliases are still there
diff --git a/tests/test_email_utils.py b/tests/test_email_utils.py
index 1137df49..126d4c61 100644
--- a/tests/test_email_utils.py
+++ b/tests/test_email_utils.py
@@ -473,10 +473,12 @@ def test_generate_reply_email(flask_client):
     alias = Alias.create_new_random(user, AliasGeneratorEnum.uuid.value)
     Session.commit()
     reply_email = generate_reply_email("test@example.org", alias)
-    assert reply_email.endswith(alias.get_domain())
+    domain = get_email_domain_part(alias.email)
+    assert reply_email.endswith(domain)
 
     reply_email = generate_reply_email("", alias)
-    assert reply_email.endswith(alias.get_domain())
+    domain = get_email_domain_part(alias.email)
+    assert reply_email.endswith(domain)
 
 
 def test_generate_reply_email_include_sender_in_reverse_alias(flask_client):
@@ -488,10 +490,12 @@ def test_generate_reply_email_include_sender_in_reverse_alias(flask_client):
 
     reply_email = generate_reply_email("test@example.org", alias)
     assert reply_email.startswith("test_at_example_org")
-    assert reply_email.endswith(alias.get_domain())
+    domain = get_email_domain_part(alias.email)
+    assert reply_email.endswith(domain)
 
     reply_email = generate_reply_email("", alias)
-    assert reply_email.endswith(alias.get_domain())
+    domain = get_email_domain_part(alias.email)
+    assert reply_email.endswith(domain)
 
     reply_email = generate_reply_email("👌汉字@example.org", alias)
     assert reply_email.startswith("yizi_at_example_org")