[Dovecot] Per user based protocol access and pause after failed login?

Hello.

Tried search, no luck, sorry, if this is already answered, but I'm still looking a solution using pam_auth how to define in dovecot which user can access which protocol, for example, default is:

protocols = pop3 pop3s imap imaps

I'd like to use something like this:

exclude_using_pop = user1, user2, @group exclude_using_pops = user1, user2, @group exclude_using_imap = user1, user2, @group exclude_using_imaps = user1, user2, @group

The idea is security and also preventing imap user by accident logging in using pop3 and downloading (clearing inbox for imap) all inbox.

And also some throttling, for example the adjustable time to pause access after failed login etc would be great.

-- Mart