Cyrus delivers claims that the mailbox does not exist

Given that you have a username john@domain.tld, unless you escape the '@' as explained below, Cyrus deliver will claim that the mailbox does not exist.

Instead of deliver john@domain.tld you should be using deliver john\\\@domain.tld.

And instead of deliver -a john@domain.tld -m user/john@domain.tld you should be using deliver -a john\@domain.tld -m user/john\\\@domain.tld

As far as the '@' is concerned, the same applies while not using the unixhierarchysep.

keywords: cyrdeliver master.cf