/etc/pam.d/webmail is in sqwebmail 0.66.1-1ubuntu4.
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 configuration file for SqWebMail daemon
@include common-auth
@include common-account
@include common-password
|