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IP Address Blacklisting Issues

September 24, 2009

Spam has been a problem for years and it seems almost impossible to address. Two years ago, Packetizer was receiving thousands of spam messages per day and we were forced to implement various spam blocking technologies, including blacklisting IP addresses. As much as we hated to do that, it became necessary, as it was otherwise impossible to find and read the legitimate email. We also began employing technologies like SPF and are also now using DKIM, digitally signing every message transmitted by our mail server.

It was never our intention to block legitimate mail servers and as issues were brought to our attention, we took immediate steps to resolve the problems. Our servers would provide a response back to senders when they are blocked and we also provided a tool where anyone can query to see if their server is blocked.

In the spring of 2009, our mail server was re-located and is now running inside Amazon's EC2 cloud service. We were assigned a static IP address and have been using that same IP address for all outbound mail since. Initially, we were somewhat disappointed to learn that our server was actually blacklisted on a few Internet blacklists. However, we were quickly able to resolve those issues with the more legitimate blacklisting organizations, such as Spamhaus and Spamcop. Unfortunately, UCE PROTECT was not very willing to cooperate. After a month of negotiating, they finally agreed to remove us from their list.

The reason our server was on their list is because we run mailing lists and some bots subscribe (or attempt to subscribe) to mailing lists using bogus addresses, to which our server politely responds with a welcome message, assuming the message passes the SPF test. (We are presently not enforcing DKIM, but will once this is generally practiced.) Unfortunately, UCE PROTECT treats those messages as spam messages and then places our server on the blacklist.

Packetizer was not listed on UCE PROTECT's blacklist for several months, but it appears we are now listed again. We attempted to contact UCE PROTECT via email and were blocked. So, there appears to be little or nothing we can do: we cannot even discuss the issue.

Unfortunately, many people on the H.323 Announce list and other mailing lists are not receiving messages and, in some cases, are being removed from mailing lists due to message rejections. Please note that this is not our fault and if you find yourself unsubscribed, definitely feel welcome to subscribe again. If your service provider or employer is using UCE PROTECT, you may wish to ask them to stop using the service.

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