I've spent the last articles writing about getting an open source email server up and running. So far so good. My email logs show that a tremendous amount of spam is being blocked. One begins to wonder if there any real email remaining any more.
During the building of this server, a number of web sites provided useful information for troubleshooting and for configuration. I'm listing them here for reference before I close them out.
- http://www.linuxweblog.com/blogs/sandip/20080206/sendmail-accessdb-example: provided useful explanations and examples of the interactions between the access database, the blacklist_recipients feature, the value part of the map, and how to use the delay_checks feature for negative or positive exception handling.
- ZEN Return Codes: The 127.0.0.x return codes. Basically, 127.0.0.2 is for direct UBE sources, spam services, and ROKSO spammers; 127.0.0.4-8 are for illegal 3rd party exploits, including proxies, worms and trojan exploits; and 127.0.0.10-11 are for non-MTA IP address ranges set by outbound mail policy
- : a good description of the sendmail.mc file, it's options,
features, and ordering. It goes into some detail about special considerations of the VIRTUSER_DOMAIN_FILE. It also goes into uses
and configuration examples of the access file.
- SPF Setup Wizard: I'm not sure if the Sender Policy Framework (SPF) is much in use, but this web size provides a wizard for it's DNS record creation.
- Sendmail Readme for Configuration: The original source for configuring Sendmail.
- Linux Home Server HowTo: Sendmail: another article on how to build a full-fledged email server. One key command for ensuring you havn't configured an open relay through a series of 19 tests: 'telnet relay-test.mail-abuse.org'. When run from the mail server, the server at relay-test.mail-abuse.org will connect back to your server on port 25 and run the series of tests.
- sendmail.mc: this is the best organized and best documented sample sendmail.mc file I've ever seen.
- xabean's sendmail.mc: example sendmail.mc with native macros and a milter, with hotlinks to relevant sections in the Sendmail Readme file.
- Hugo van der Kooij's sendmail.mc: looks like he no longer runs sendmail, but here is his sendmail.mc with some native macros.
In some follow-up, I came across MailWatch, which is a web-based front-end to MailScanner written in PHP, MySQL and JpGraph and is available for free under the terms of the GNU Public License.