Controlling IP addresses for services

[Alex]

Hi,
I'm using dovecot-2.2.15 on fedora21 and would like to configure pop3s
and imaps to only listen on localhost and internal addresses.

It seems the listen= parameter only supports ports, not IP addresses.
Is it possible to control which IPs the services listen on?

I'm also interested in knowing the differences between pop3-login and
just the pop3 service? Same with imap-login and imap?

I've searched the wiki and still a bit confused.

Thanks,
Alex