Testing Different Mail Server Configurations?

bsaxon asks: "I am looking for advice on methods that would allow the testing and debugging of different mail server configurations, particularly different ways of handling spam and mail filtering. What are different ways that different mail configurations can be tested? Currently, we have two servers running Linux that check all incoming/outgoing mail for viruses and spam, using software that works with Sendmail. After incoming mail is processed, it is relayed to its final destination, in a mailbox on a MS Exchange server. One server handles the actual processing of mail, and the other server just queues mail when the other server is down or overworked. Basically, I would like to have all mail duplicated, before reaching any filters or virus scanners or blocklists, with one copy continuing its normal route to the production server and the other copy of the message going to the test mail server. Can it be done at the DNS level or through Sendmail or are there other ways that this could be achieved? I am only looking for suggestions that deal with different methods of testing different mail server configurations, not actual suggestions for filtering mail."

Comments

Use of qmail - simple solution

[under_score]

I use qmail for my servers and it can do this quite easily in a number of ways. There are lots of good online documents about qmail as well as the official qmail site. The simplest method is probably a default install with a .qmail-default file in the alias directory which has two entries in it. Each entry could be a different destination email address or local account. This would certainly duplicate the email coming through, but may not be the best way to do your job. Working with the qmail-smtpd program may get you a solution closer to your needs. Good luck!

Since nobody's actually answering your question...

[isaac]

Yeah, so nobody actually read your question. Welcome to slashdot and sorry about that. You really need to understand how email and the internet work a bit better if you thought DNS could do this for you. What you're asking for is a slightly more difficult problem than just "sendmail | tee -a foo".

If you're stuck on sendmail, these might help:
http://www.nber.org/copy-out.html
http://www.milter.info/sendmail/milter-bcc/

If you want to give other MTA's a whirl for this purpose, google "tee postfix" and see the postfix mailing list thread or try that qmail foo suggested by another poster.

Basically, there are different "problems" with each method, but it's late and I want to go home so you'll have to do your own homework. A few likely complications: recipient checks, source IP checks, header munges interfering with spam filtering

-Isaac

Nitpickers university

[majello]

Hi!

Sorry to be annoying, but i consider your approach - while intuitive - basically flawed. If you are testing with constantly changing input data, it is very hard to determine the effect of any changes to your configuration. What you would do instead is capture a days worth of data, or maybe more, and hack together some script that lets you replay the day against you test configuration. thus you can always make suer that any changes you made haven't messed up the configuration. you can also vary replay speed to do some stress testing, and you might want to consider building up a set of "interesting" mails to use as testcases.

testing with an unknown and essentially random input set has its values, but i consider it incomplete.

cheers, Stefan