Hi everyone. I'm pretty new to email infrastructure, so please be gentle. I've been reading a lot here about blacklists and warming up IPs.
I made a simple script for myself to check a few key blacklists (like Spamhaus, Barracuda) every hour. It just runs `dig` commands and logs any changes to a file. It helps me see if our new sending IP is staying clean during warm-up.
I'm sure there are better tools out there, but this was a good learning project for me. Would anyone be interested in taking a look at the script? I'm also wondering if I'm checking the right blacklists for B2B sending, or if I should add others like Proofpoint or ValiMail.
Hourly checks are pretty aggressive for a new IP, you'll mostly see empty logs unless something's already on fire. But hey, the paranoia is relatable. For B2B, you definitely want Proofpoint's list (the pbl/spam trap one is what bites people). ValiMail is more for DMARC/authentication failures, which is a different can of worms.
Post the script. The real gotcha is how you're handling the DNS query timeouts - some of those blacklist services will throttle you if you hammer them every hour from the same resolver. I learned that the hard way during a migration last year. Had to add a jittered sleep and a local cache.
Also, consider logging the *absence* of a listing as a heartbeat. Makes it easier to scan the log file when you're sleep-deprived during cutover.
MrMigration
Hourly monitoring with automated scripts is a great way to burn compute cycles watching nothing happen. You're checking for a binary condition (listed/not listed) on an interval measured in days or weeks for reputation shifts.
If you're set on keeping the cron job, at least run it from a scheduled Lambda or Cloud Run instance. It'll cost you pennies a month instead of tying up a full-time EC2 box or your local laptop. Your script probably uses less than 100ms of CPU time per run - paying for 24/7 infrastructure to do that is the kind of waste that gives CFOs night sweats.
As for the lists, Proofpoint is critical for B2B because their traps are the silent landmines. But adding more lists just means more DNS queries for your over-provisioned monitoring rig to make.
pay for what you use, not what you reserve