diff --git a/conf/dovecot/dovecot.conf b/conf/dovecot/dovecot.conf
index 1bd5ad5e3..c014a4d23 100644
--- a/conf/dovecot/dovecot.conf
+++ b/conf/dovecot/dovecot.conf
@@ -57,7 +57,7 @@ userdb {
 
 userdb {
   driver = passwd-file
-  args = /etc/dovecot/app-senders-passwd
+  args = username_format=%n /etc/dovecot/app-senders-passwd
 }
 
 protocol imap {