Spam Blocklisting

How spammers are stopping your email from ge3tting through

If you've come to this page it's probably because you've received an email bounce that says your mail isn't being accepted at because of the SORBS or Spamhaus blocklists. You can reach us by getting an email address from a free email provider that isn't in the blacklists.

If that hasn't answered all your questions, the information below may address the issues in more detail.'s IP blacklisting Q and A:

A: In fact, no blocklist actually blocks your email or anyone else's. is the one bouncing your mail from our server. We are doing so based on the list of IP blocks belonging to ISPs that provide support for spam operations, but we are the ones keeping your mail off our server, not any blocklist.

A: Blocklists have a right to block anyone they want from their own system. And they have the right to publicly state who they're blocking. Other domains (like have the right to use blocklists to establish their own blocking practices if they so wish. And we do so wish.

An analogy: Roger Ebert has the right to publish his reviews of movies and I have the right to not go to see movies he doesn't like. If his judgment is poor I'll miss out on seeing some great films, but that's my choice. Just as I can base my choice of movies on the judgment of a third party like a reviewer, system operators can base their connectivity decisions on a third party blocklists. Keep in mind that the Internet Providers who use blocklists are, by and large, doing so because their customers have asked them to do so.

By the way: There are many third-party spam-filtering blacklists. If you enter the blocked IP address into the form here you may be surprised to find that it's on many other blacklists as well.

A: There are two answers to this question, a long one and a short one.

The short one: Blocking just the individual offending IP addresses has been tried in the past and it was ineffective.

The long one: The objective is to cure the disease rather than just treat the symptoms. Experience has shown that if only the offending IP address is listed, the spammer will just keep spamming, not knowing or caring about the bounces. The spammer's host can keep the spammer connected and keep collecting a monthly check. While millions of unprotected addresses keep receiving the spam. Lately, some abusive ISPs have gone a setp further when just one or two IP addresses are blocked: They shuffle their spammers around to new (unblocked) IP addresses as soon as one address gets on a blacklist. The only way to effectively deal with this is by listing entire blocks of IP addresses.

Widening the range of blocked IP addresses serves two purposes: It lets the other, legitimate, customers of the ISP or web host know what kind of company they're doing business with, and it puts pressure on the web host or ISP to clean house to avoid losing all their customers, not just the spammers.

A: Blocklists are not necessarily lists of spammers; they may also include ISPs that provide support for spam operations. You're blocked because your provider harbors people who are spammers. To put it another way: You're being shunned because you live in a bad neighborhood.

Imagine that you're a fine, law-abiding, middle-class citizen who moves into an apartment building in the slums, with crack dens, street gang members and prostitutes occupying many of the other apartments in your building. You'd find pizza parlors would refuse to deliver to your neighborhood. Your friends would never come to visit you. (They might even start avoiding you altogether.) Of course you'd never do that in real life, but on the Internet you can't see your neighbors, so it's possible to move into the cyberspace equivalent of slum without knowing it... until your mail bounces because other ISPs are refusing connections. This is apparently what's happened.

First the wise-ass answer: "If life was fair Elvis would be alive and the impersonators would be dead."

Now the real answer: If you're the customer of a blocklisted ISP or web host, every monthly check you write to your provider helps support a business that harbors (and profits from) spammers. You've become a spam supporter without knowing it. Your support is of the most valuable kind there is: money. You're being blocked because you're contributing (albeit unknowingly until now) to the problem.

A: It depends if you're a spammer, an ISP/web host or a legitimate customer of an ISP/host that's been listed.

If you're a spammer you can either stop spamming or move to another ISP/host. (And then another when that one get listed. And then another, and another... Better get used to moving around a lot.)

If you're the Host or ISP you need to boot off your spammers (and those who sell spam software).

If you're a non-spamming customer who's been caught in the net cast over your ISP/web host you have two options: You can move to another provider who doesn't value spammers' business over that of legitimate customers like you. Or you can contact your ISP/host and insist they get rid of their spammers. When enough people either leave or complain the spammers will get the boot, because the prospect of losing legitimate customers will simply make it to costly to keep the spammers.

There are many thousands of ISPs that are not listed by blocklists, including many small "mom and pop" Internet providers. If your ISP or web host can't keep their servers off SPEWS list they aren't giving you the full service you're paying for. They are, in fact, ripping you off.

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Copyright © Mark Roberts