While I want to be able to receive email from people previously unknown to me, regarding my web pages, work, and newsgroup postings; I don't want to receive unsolicited bulk email. I also want to block my web pages from annoying bots.
I currently block stuff at wolff.to based on the following:
#!/bin/sh exec 2>&1 \ /usr/local/bin/tcpserver -vRDHl0 -u 0 -g 0 -x tcp.cdb 0 smtp \ sh -c ' \ /usr/local/bin/tcpclient -q -T 5 -H -l unknown \ "$TCPREMOTEIP" smtp /bin/true && \ exec /var/qmail/bin/qmail-smtpd \ || \ echo "451 Unable to verify remote mail server"'
My mail at UWM gets extra scrutiny, since I can't control who gets to send stuff to their hosts and they do some internal spamming, I use mail filters to drop messages based on a number of idiosyncratic rules.
There is also a domain block list for poorly run run mail servers, RFC-Ignorant. Their system doesn't integrate well with stock qmail and they don't provide data other than by DNS lookup, so I am not currently using them. However, when I find places that reject bounce messages and the like, I add their domains to my badmailfrom list.
I have also written a program that generates web pages with bogus email addresses. I have mapped a whole class of addresses (robot.*.html) to this program using my .htacces file. This is depreciated in favor of the system mentioned above.
To find out more about netiquette you can read rfc 1855 and rfc 2635 .
A secure version of this page is located at: https://wolff.to/bruno/antispam.html