Open Source Mail Gateway

I hinted over in a post in OS that I was working on a mail gatway/relay for my exchange server. I have used other commercial products in the past and was thinking on spending some bucks on perhaps GFI or McAfee or any other host after host of packaged, and expensive products. But then I realized after licensing the product, licensing the windows box and activating the server that I would consider taking a new approach and get the dust off my linux admin books and learn more of the mail delivery process in general. The idea here is not to eliminate Exchange but to isolate it and off load spam checking and virus scanning. I consider those a SECURITY Issue versus productivity. The virus scanner on Exchange will remain for additional layers, but one could eliminate that cost if desired. This is not a tutorial, there are many already. This is the start of a discussion for the cool linux folks and in my case to show off a weeks worth of detailed work, name the software involved so far, and then go have a BEER. :D And I am only half way through.... it took a long time to get all those OKs. Note I am NOT using Postres SQL.

After my BEER I can discuss the modules installed thus far and what they do in the grand scheme of things. Next stop, website access for the database so that users can veiw what has been snagged and anyone else that wants to join in and build a FREE web gatway with some kick ass tools.

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amavisd-new:

file(1) : 4.14 : OK
Archive::Tar : 1.24 : OK
Archive::Zip : 1.16 : OK
Compress::Zlib : 1.35 : OK
Convert::TNEF : 0.17 : OK
Convert::UUlib : 1.051 : OK
MIME::Base64 : 3.05 : OK
MIME::QuotedPrint : 3.03 : OK
MIME::Parser : 5.417 : OK
Mail::Internet : 1.67 : OK
Net::Server : 0.88 : OK
Net::SMTP : 2.29 : OK
Digest::MD5 : 2.33 : OK
Data::UUID : 0.11 : OK
IO::Stringy : 2.110 : OK
Time::HiRes : 1.66 : OK
Unix::Syslog : 0.100 : OK
DBI : 1.48 : OK
DBD::mysql : 3.0002 : OK
DBD::Pg : N/A : NOT INSTALLED (required if you want to use Pos tgreSQL)


SpamAssassin:

Mail::SpamAssassin : 3.000004 : OK
File::Spec : 3.05 : OK
Pod::Usage : 1.3 : OK
HTML::Parser : 3.45 : OK
DB_File : 1.811 : OK
Net::DNS : 0.53 : OK
Digest::SHA1 : 2.10 : OK


Maia Mailguard:

Crypt::Blowfish : 2.09 : OK
Crypt::CBC : 2.14 : OK

Database DSN test : PASSED

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There is also plenty of docs on opensuse.org

Have you tried DSPAM its great, I prefer it to Spam Assassin.

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Have you tried DSPAM its great

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No I didn't really try that one. This is my first Linux mail gateway so I opted for programs that seem to be popular. I have loaded it about 5 times so far trying to get everything to work. Which was my excitement in the first post. ;) At current I am using Postfix as the MTA (mail transfer agent) that port forwards mail internal and through Amavisd-new. Amavisd-new is the virus scanning engine that calls SpamAssasin which does both DCC checks and Razor2 checks. I love the theory and practice behind DCC (Distributed Check-sum *************) where incoming messages are assigned a check-sum that is compared to what other servers are reporting. If a threshold of similar messages is met at DCC it marks the message as spam. Razor is a typical spam filter with clients reporting spam along with the canned signatures and tests included with SpamAssasin . I would bet without DCC and Razor2, SpamAssassin wouldn't be very effective in my case?

The Amavisd component (that calls SpamAssasin which in turn calls Razor2 and DCC) also checks for RFC compliance in headers, addressing etc. Then the bonus is, it calls ClamAV which is an excellent virus scanner. All this info gets dropped into a MySQL database created especially for Amavisd through scripts. One of my major concerns with an open source project was managing the requests that would come from customers, so to manage the whole thing I chose Maia Mail Guard

Maia is a web front end and it pretty much written in PHP using Pear modules. The interface is excellent and users are automatically created and mailed log-on credentials as the system sees incoming mail that is valid for this domain. I am still tweaking the UI but right now users get a notification list of spam and they log in and are presented a screen that has their spam distributed into categories. It is very easy to manage this system from the front end.

The only drawback, and I wouldn't even call it that compared to the power I now have over my gateway, is the lack of integration into Outlook. Outlook is proprietary. There are some experimental authentication models for Exchange 5.5 but who runs that? So I am not even bothering with integration. The flip side is Exchange does not have to process spam on the clients and server, like I do now. That overload of information is shifted upstream. Users in my opinion will be able to receive and process valid mail much quicker without integration.

Next lock down and roll-out. All the linux dudes are probably saying big deal. :D This is directed at the casual linux user/admin and windows security and systems administrators. Because Windows users... outside of my time and a 300 dollar computer this system is OPEN source, has no licensing fees, is easy to operate ONCE installed and KICKS ASS. One caveat, there are some licensing issues for Maia IF you remove all the logos. I customized my install but left all the author logos and credits. After all the Maia dog is cool. It's always a good idea to read licensing.