[Dovecot] Master User Question

OK - I'm trying to do weird stuff so rather not answer why I'm doing this.

Trying to log in using a master user:

user@example.com*master@master.com

When debugging the master authenticates - but then it tries to authenticate user@example.com and it's not found. And - it is true that the user doesn't actually exist.

What I want to do is allow it to log in without checking if the user exists, just on the credentials of the master.

I'm not quite understanding what the login attempt for user@example.com is trying to do. Is it looking for more necessary information?

Hope I asked this clearly enough. Thanks in advance.