/etc/pam.d/dovecot is in dovecot-core 1:2.2.33.2-1ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | #%PAM-1.0
@include common-auth
@include common-account
@include common-session
|