Ask Al: Senderbase.org?

A reader wrote in with the following question/complaint about Senderbase.org. I'm going to post this one anonymously. The reader wrote, "I would like to request a review of senderbase.org. I would like to know if I am the only one that has communication problems with them. Their delisting instructions are basically non-existent, and my last attempts to communicate with them have takes upwards of two weeks to even get a response. I believe the listings last an incredibly long time and that their communication and delisting process is extremely poor. I would like to know what your opinion of them as a reputable RBL would be. Perhaps it is just me with the problem."