Postfix and DNS kung-foolery


I was asked to send out an email to a list of a few thousand recipients, for an upcoming event. The first thing that came to mind was how long it was going to take to get our IP address off the blacklists. After a few moments of cold sweats and hiding in a corner, I formulated my plan.

1. Download PHPList and got it installed on my LInux intranet server.

2. Create a PTR record in our reverse DNS zone for one of our public IP addresses to listmaster.companydomain.com

3. Adjusted the firewall to NAT any TCP communication coming from the intranet server to the public IP address I specified in the PTR record.

Now all bulk email goes out over an alternate IP address, that properly reverses, and our primary company IP address is safer from black listing. I say safer, ’cause some blacklists ban the whole IP block, which would be….very bad.

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