If you run a mail server on your slice and find that email sent from your server is being rejected as potential spam, your slice may be on the Spamhaus PBL. Don't be alarmed — that's actually pretty normal. This article will tell you how to get off the PBL quickly and easily.
The Spamhaus policy block list
Spamhaus assists Internet service providers with preventing unsolicited email (spam) from passing through their mail servers. One of the tools Spamhaus employs is a "Policy Block List" (PBL) that lists addresses that get assigned to customers of dial-up, broadband, and hosting service providers. Those addresses are then blocked by default and have to be manually removed from the list when someone has a legitimate need to use one of those addresses to run a mail server (as many Slicehost customers do). It is therefore likely that a new slice, or one that hasn't been used as a mail server before, will be on the Spamhaus PBL.
Being on the PBL doesn't mean your address is blocked for spamming. The list is only there as a precaution against potential abuse. Spamhaus applies this policy to any IP addresses that could change hands from one customer to another. Their goal is to prevent computers that should not be sending email directly from being able to do so if they are compromised in some way.
How to get off the list
Fortunately it's easy to check the Spamhaus PBL to see if your slice's IP address is on the list, and it's also easy to remove it. Go to the Spamhaus Block List Removal Center and enter your slice's IP address. If your address is listed in the PBL you will be provided with a link you can use to remove it. Note that the removal process requires the use of an email account that is not part of a free service (like gmail.com or hotmail.com). Since the PBL does not prevent a mail server from receiving mail (only from sending it to destinations that employ the Spamhaus service), you can use an email address from your blocked mail server for the Spamhaus verification process.
- -- Jered