Full Mail Server Solution w/ Virtual Domains & Users (Debian Etch, Postfix, Mysql, Dovecot, DSpam, ClamAV, Postgrey, RBL) - Page 14
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VIII. Final Words and Sources
So, assuming you've followed this guide through to its entirety, you should have one fully functional email solution. You've got a primary and secondary MX, a mail delivery server, a secure mail server, and a healthy dose of spam and anti-virus protection.
Does that mean you can just push the 'GO' button and walk away? Absolutely not. First off, you're going to want to run the system through a number of tests... test everything. Try sending mail using your primary & secondary MX's as your SMTP server (it shouldn't work), try sending mail using your secure mail server, but without security settings enabled in your client (It also shouldn't work). Try everything, and then when it's all working, try it again. You don't want to go rolling this setup into production without having tested it thoroughly first.
In addition, it's entirely possible that something (or some things) are incorrect in this guide. A large portion of it was written from memory, and that always opens you up to a hole or two. If you find a glaring error, feel free to drop me a line, and I'll get it fixed. This is a long guide, I wouldn't be surprised if there were a few glitches in it.
Finally, I'd like to send out a 'Thank you' to the various people who helped me write this guide. There's more than one source that I 'borrowed' from verbatim, and I couldn't have written this without them. In no particular order: