[NTLUG:Discuss] How to dump a list of email addresses from your mail server?

[Daniel Hauck]

I'm preparing to deploy ESVA (a vmware appliance for email filtering) at
home.  I have been using it at work with fantastic results.  One feature
on there that is absolutely necessary is to specify the relay_recipients
for Postfix to use, rejecting all other incoming emails.  To simply
accept all email for a domain will result in thousands of different
random email addresses being sent to my domains, each being filtered and
scanned before finally being rejected by the actual email server.  It
results in a HEAVY processor load and I don't want it.

At work, we have an exchange email server and with a handy-dandy Perl
script that does some LDAP magic, I am able to download a list of all
email addresses from the exchange server and feed it to ESVA via an
hourly cron job.  (This allows me to simply add or delete a user and the
list will update itself within the hour automagically)

I want to do the same thing at home but the problem is, I don't have any
such LDAP thing running at home... I'm all Linux and it's set up rather
simply.  So, with that said, what would be an easy way to have the
mail/web server I'm loading generate a list of valid email addresses for
the domains I'm hosting?  This would be accounts *and* aliases.

I suppose performing multiple steps where I scan the passwd file and
then the aliases file might work but I'm no shell or perl script wizard
to be sure.  So before I do it "the hard way" I'm hoping someone with
superior skillz could show me what a dummy I am by showing me an easier way?