UCEProtect is a IP blocklist that mail server owners can use to block certain IP addresses from delivering emails to their users. It is a system that is a useful spam indicator, in conjunction with content analysis, link analysis and other tools.

However, UCEProtect have a massive failing - they tend to block IP address ranges (rather than a single IP address). This will help with the spammer that use changing IP addresses, but also will block countless other users.

At the moment, they have blocked an entire range of BT email servers (BT are one of the largest ISP's in the UK). A large number of emails are being rejected by users of this block list. There may indeed be some spam emails being generated inside this IP address range, but there are also thousands of genuine, legitimate emails being blocked.

Any effective Spam solution has to BOTH block spam AND allow genuine emails through. Blocking a large IP address range totally fails the second part of this test.

BT have apparently contacted them about this, but they are asking for a large amount of money to remove the IP block. I will leave it to your own judgement to decide if this is a legitimate administration charge to solve a problem they created in the first place. Their website says that any complaints about extortion will result in a permanent IP block.

If you are a mail server admin, I would strongly recommend looking elsewhere for a IP block list, or only using UCEProtect as a single scoring aspect, not as a 100% spam failure.