[Dovecot] Easy way to make all mailboxes of a user read-only

Hello all,

I try to configure dovecot to make all imap accesses read-only for a certain user. I thought this would be possible by creating a global acl file (here "global-acl") like:

user=<username> lr

and

plugin { acl = vfile:/etc/dovecot/global-acls:cache_secs=300 }

But that seems to be ignored. What is wrong with this idea, the docs are not really clear about a single acl file with global settings.

-- Regards, Stephan