Email fowarding to same domain (internally) fails. Mail Delivery System: "Unknown user"

[Ilia]

@kylegp

Any idea why Roundcube webmail isn’t letting me log in when I create a new user now

Postfix virtual map escapes some @

Instead, do you have any issues by disabling virtuser_file plugin completely by editing roundcube/config/config.inc.php file and removing virtuser_file from plugins list.