diff --git a/django_mailbox/models.py b/django_mailbox/models.py
index 27faa60..6b76d26 100644
--- a/django_mailbox/models.py
+++ b/django_mailbox/models.py
@@ -352,7 +352,7 @@ class Mailbox(models.Model):
                 )
                 msg.set_payload(
                     msg.get_payload(decode=True).decode(
-                        content_charset,
+                        'ascii',
                         'ignore'
                     )
                 )