How do ESPs handle blocklist events?
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You hit send, your emails stop landing, and you have no idea why. Then you find out your ESP's shared IP is on a blocklist. What actually happens next, and what's your job versus theirs?
Reputable ESPs watch their infrastructure around the clock. When a blocklist event hits one of their IPs, the response usually kicks off fast. They figure out which account or campaign triggered it, then decide whether it was a policy violation, a technical error, or something like a spam trap hit.
On shared IP pools, the stakes are higher because one bad sender can drag everyone else down with them. Most ESPs will pause or suspend the offending account to stop the bleeding before the rest of the pool gets hurt. If you're a clean sender on that same pool, you might see a brief disruption even though you did nothing wrong. That's the trade-off with shared infrastructure.
The ESP then handles the delisting request directly with the blocklist operator. Spamhaus, Barracuda, and others have formal processes for this. ESPs deal with these operators regularly, so they usually know what documentation is needed and how to get an IP off the list faster than a solo sender would.
Here's where your responsibility comes in. The ESP fixes the infrastructure problem, but they can't fix what caused it on your end. If your list was stale, your complaint rate was climbing, or you sent to addresses you shouldn't have, that's on you to correct. Expect a conversation with your ESP's compliance team, and expect them to ask you to clean your list before you're allowed to resume sending at full volume.
Worth knowing: if you're on a dedicated IP, a blocklist event hits only you. Your ESP won't suspend you to protect others, but they also won't rush the delisting on your behalf without your involvement. You're more in the driver's seat, for better or worse.
If you want to catch blocklist issues before your ESP calls you, our free Blocklist Checker lets you scan your domain or IP anytime. And if things are broken right now, the SOS hotline is free.
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