diff --git a/mail4one/server.py b/mail4one/server.py
index f5427fe..5bcbfb7 100644
--- a/mail4one/server.py
+++ b/mail4one/server.py
@@ -8,6 +8,8 @@ import sys
 from argparse import ArgumentParser
 from functools import partial
 from pathlib import Path
+# noinspection PyUnresolvedReferences
+import encodings.idna
 
 from aiosmtpd.controller import Controller
 from aiosmtpd.handlers import Mailbox