Description of problem:
Users sending email via Squirrelmail trigger complaints that sendmail is
sending with -f, without a user being listed in /etc/mail/trusted-users.
Example from sendmail's logging output (with identifying info altered):
Jul 30 14:16:16 hostname sendmail: xxxxxxxxxxx: Authentication-Warning:
XXXXX.example.com: apache set sender to email@example.com using -f
Version-Release number of selected component (if applicable):
Steps to Reproduce:
adding apache into trusted-users removes the issue. Would recommend this
approach, but it should be documented as there could be implications if there
are virtual hosting setups on the same server.
This is something that individual mail admins should address because,
as you say, SquirrelMail might not be the only program on the server
that is sending mail.