[Dovecot] Authentication listener configuration

Hi,

I'm wondering about the authentication listeners that dovecot uses. In many configurations I see: service auth { unix_listener auth-userdb {

Does any component of dovecot use this listener internally (lmtp, lda ...) and does that read the config and search for the listener, or is the exact name "auth-userdb" expected? Is this maybe dependent on the userdb? Which ones need it? And if I want to use postfix SMTP auth, should I define a second listener, or just re-configure that default one to postfix's needs?

Also, in which cases do I need to define an auth-worker service, and a unix_listener for it?

I don't find this in the documentation, if that's caused by my lacking search skills, please just send apointer.

Thanks

Rainer