IP Address Blacklisting

If you're reading this, you have gotten an email bounce message saying that your IP address was blocked from sending mail to acme.com. You're probably wondering why. We have a number of different IP blacklists here, your address could be on any of them:

This is not a complete list, there may be others. Most of these blacklists expire entries after a few days. If we still see lots of connection attempts during the blacklist period, we keep the listing around until it shuts up. And a few addresses have earned permanent listings.

If you get your IP address from your ISP via DHCP, instead of as a permanent static address, you may have gotten an address that the previous owner was abusing. If you find yourself blocked from sending us mail because of this IP address reuse effect, you have a few options:

It's also possible you're sending mail through your ISP's SMTP servers, but other customers of the same ISP using the same servers have worms. If this is the case I need you to do two things:

As for why we're doing this: before we started IP blacklisting, crapmail was using up almost half of our incoming bandwidth. Now it's down to only about 15%. The blocking is accomplished using blackmilter, a nice simple tool that can efficiently block millions of IP addresses.

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