iRedMail is:
1. A ZERO COST, fully fledged, full-featured mail server solution. All components are free and open source software
2. It support unlimited domains and email accounts.
2. SpamAssassin, ClamAV, SPF, DKIM, greylisting, whitelisting, blacklisting.
3. Stores mail accounts in your favourte backend: OpenLDAP, MySQL, MariaDB, PostgreSQL.
4. Supports major Linux distros
You know how difficult is to configure a fully fledged email service you have tried. iRedmail do this heavy part for you. I would recommend this piece of software to everyone. I used to configure email server manually using Postfix, Postfixadmin, MySQL, SpamAssassin, etc. Even though I have done this several times, it needs 2-3 hours for setup. But iRedmail can do all of this and MORE in few minutes, thus saves lot of time.
Reject outgoing Spam
iRedmail comes with Amavis, Spamassasin and Clamd. By default iRedmail will not block Outgoing spam message. However you can tweak Amavis configurations to reject such mails.
/etc/amavisd/amavisd.conf
Add following to $policy_bank{‘ORIGINATING’}
final_virus_destiny => D_DISCARD,
final_banned_destiny => D_REJECT,
final_spam_destiny => D_REJECT,
final_bad_header_destiny => D_REJECT,
Then restart amavis /etc/init.d/amavisd restart
This will reject all outgoing spam mails above the score
Of course tweak the spam score accordingly.