Using the snap package for Ubuntu - no permissions to compress mboxes in /var/mail/

[EmTee70]

As mentioned above, I have problems to use the snap package to compress folders from users in /var/mail
I first have to move them to the home of the owner, compress them and than move them back.
While this is possible it is not so convenient as before, when it was possible to easily delete old files from folders in /var/mail.