I have a rather strange, atleast to me, issue relating to the Spamcop's spam traps.
We run a rather large membership site (around seven million members). To support various site features we run two mail servers. Each mail server sends different types of mail, but they both send to the same list of users.
Over the last three months, one of the mail servers has been blocked atleast 3 times for sending mail to spam traps. The other server has never, to the best of my knowledge, been blocked. The server that was blocked is the newer and lower volume of the two servers. Both mail servers would have sent to the same addresses, so if one got blocked the other probably should have as well.
Are there any conceivable circumstances that might explain why one server gets blocked and the other doesn't?