daily system administration

Linux, Debian and the rest
any questions or comments: Tom@d7031.de

better individual spam defense with amavis and spamassassin

Postfix, amavis and spamassassin is a very good team for handling emails and fighting against SPAM. They catch ninety percent of all SPAM with there ruleset. You can also include the excellent ruleset from Heinlein-Support (german). But. I’ve some special SPAM for health ensurance advertising and so on. So I’ll show a way to catch this last percents. My email setup is very common. Postfix takes the email and delivers these to amavis. Read more →

Postfix and lost connection after DATA

Trouble with immature firewalls and postfix. I run into trouble with one postfix server. This server is located behind a firewall and I got the error postfix/smtpd[1434]: lost connection after DATA from … in the mail logs. Debugging postfix with debug IP-address shows nothing unusually. So it must be another reason for that. Searching around the first match is a problem with MTU and the absense of ICMP between the firewall and the postfix-server found on Heinlein Blog. Read more →

Postfix and TLS (outdated)

After securing your mail-relaying between postfix as smarthost and postfix on a road-warrior, the next step to do is securing the transport way. E-Mail is clear text! Every (machine) can read it! Think about a open WLAN. The hotspot-provider can read your Mail! I’ve tested this setup with Debian Etch and Lenny (Postfix 2.3.8-2+etch1 and .2.5.5-1.1). First you need certificates. In this setup, these are used to encrypt the mail-transport NOT for authentication. Read more →