To maintain the relay's mailertable based on the DNS, we have a Perl script called, appropriately enough, make-mailertable. This script is run on the primary relay mailer, and the results are pushed to the secondary mailer with another Perl script called, hang on to your hats, pushfiles. The dependencies are managed in a Makefile, where the mailertable depends on the domain's zone file (which through happy coincidence resides on the same machine), and the "touch file" depends on the mailertable to ensure pushes to the secondary as necessary.

The make-mailertable script dumps our DNS zone and extracts the list of hosts (in our zone) for which we MX, including their CNAMES (again, in our zone). It then constructs a mailertable based on this list, and:

• a "hardwired" mailertable, which contains hosts for which special processing is needed, including subdomains which don't run their own spam-proof relay mailers,
• the relay's sendmail.cw file (list of its own names),
• a list of registered mail receivers, which are machines that are known to be valid mail servers, and
• a list of patterns which identify machines which should not receive mail at all.

Please note that the sample files listed above are only examples; they were in use as the real files in December 1998, but will have changed since then. We also have a sample result mailertable for you to see.

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Copyright, © 2003, Concordia University, Instructional and Information Technology Services (IITS). Author: Anne Bennett Credits: (none) Maintained by: postmaster@concordia.ca Last update: 1998/12/23 -- Anne Bennett