Your server IP on a blocklist: how to tell and how to get off

A blocklist — the older name is blacklist — is a public register of IP addresses caught sending spam. Mail servers around the world check those lists before accepting a message.

If the IP that sends your e-mail lands on one, messages stop arriving. And worse: often with no warning. The recipient never sees them, not even in spam, and on your side they look sent.

First: is the IP yours or ours?

This changes everything, and it is the step most often skipped.

If you are on… Who handles it
Shared hosting or reseller The IP belongs to the server, so it is ours. Open a support request and we handle it — do not fill in removal forms on the server’s behalf
VPS or dedicated server The IP is yours. You request the removal, and we help with anything server-side
Do not request removal before fixing the cause. An IP that is removed and then sends spam again gets relisted, and the second time it comes off far more slowly. Close the tap first; only then mop the floor.

Confirming that it is listed

1 Find the IP that sends your e-mail — see what your hosting IP address is.
2 Check it with a tool that queries several lists at once. The two most used are MXToolbox (its Blacklist Check) and HetrixTools, which has the advantage of showing the removal link next to each list.
3 Note which lists it appears on. Each has its own process, and there is no single request that covers them all.
Not all lists carry the same weight. Some are queried by half the world and genuinely stop mail; others almost nobody uses. If you are on an obscure list and your e-mail arrives fine, it is probably not worth the effort.

Why an IP ends up there

It is almost never malice. The real causes, in order of frequency:

Cause How it is fixed
A mailbox with a stolen password Someone got in and used it to fire off spam. Change the password and turn on two-factor authentication
An infected site An injected script sends silently. See how to tell if your site has been compromised
A badly built form An unprotected contact form becomes a spam machine in the hands of a bot
Badly run bulk sending Bought lists, no unsubscribe, or everything at once. See how to write an e-mail that does not land in spam

Requesting removal

Once the cause is fixed:

1 Go to the removal page of the list in question. HetrixTools gives you the direct link for each one.
2 Fill in the IP, an e-mail address you can actually read, and the reason. Write what you fixed, not just “remove me” — there are people reading on the other side.
3 Submit and keep the request number.
4 Wait. Most lists respond within a few hours to a day. Resubmitting hourly speeds up nothing — on some lists it slows things down.
Coming off a list does not repair reputation. Getting off is the first step; trust is rebuilt over weeks of clean sending. In that period, send little, and only to people expecting your messages.
If the problem is only with Outlook and Hotmail Microsoft runs its own reputation programme for server operators, and the route there is different. Tell us and we will point you to it.

What prevents nearly all of this

Reverse DNS configured, e-mail authentication in order, and strong passwords — PTR and reverse DNS and SPF, DKIM and DMARC. With those three, an IP rarely ends up on a list.

Your e-mail stopped arriving and you suspect a block? Send us the domain.

Request a check

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