The file contains a path to the maildir of a non existing mail user

id:content-path-folder-fits-and-vmailmgr-user-not-exists

This error indicates that the qmail file redirects mails to a maildir path but there is no mailuser configured for this address.

Because this should currently not work and incoming mails are just bounced back you are save to remove the qmail file so mails are correctly rejected in the first place.

Warning

Warning: We could migrate this setting automatically to the standard mail system, but it might have minor effects to the current behavior of the mailaddress. You could change the configuration yourself using the uberspace mail commands.