Do mail users have to have 'users' status?

[andycrofts]

Hi.
As usual, a gap in my knowledge I can't find a one-liner for.
I'm using postfix/squirrelmail, and it's working a treat (RH9)

Stumped on this one..
At the moment, the only people who can have a mail account on my server (oululife.com) are the registered Linux users (andy, anne, root, fred)

Let's say for example that I want to give a friend free e-mail access, so his mail address would be
john.thomas@oululife.com (for example)
So far, my understanding is that I need to make a Linux user called "john.thomas". However, the more I think about it, the less likely it appears. OK, no shell, but I can't do 'no home directory' 'cos squirrelmail needs to put drafts, trash, etc. someplace.

Have I totally misunderstood (likely), or am I confusing different mail systems?

Pointers to some howtos would be very helpful.
Searching google gives too many (irrelevant) links

-Thanks
-Andy

[Radar]

http://www.gentoo.org/doc/en/virt-mail-howto.xml

This goes into using SASL to pass auth info to PAM, so users need not have unix account, but with IMAP, they still need IMAP dir with all the folders etc. You may need to overhaul your mail setup if your using mbox style mail. This is all off the top of my head. So... legal disclaimer ..etc

[andycrofts]

Thanks, Radar!
-Andy