Josh reports mail from MobileMe to spamcop.net addresses is being filtered somewhere and isn’t being delivered or actively bounced. He asserts that Apple is blocking all mail to Spamcop addresses
because they were having problems getting blacklisted on SpamCop and implemented this as a way of reducing their number of SpamCop spamtrap hits.
That makes no sense. Spamcop spamtraps are rarely hosted on spamcop.net. I won’t say never because there may be some, but I know that some spamtraps are on different domains and different SMTP servers. Senders who try to avoid Spamcop problems by filtering all mail to Spamcop are doomed to failure.
The problem is being discussed both on the Apple forums and the Spamcop forums. There is some confusion about what is going on. Some posters seem to be having problems mailing addresses at spamcop.net addresses, other posters seem to be having problems forwarding spam to the spamcop reporting address.
One poster reported that Apple support is claiming that Spamcop is blocking mail from MobileMe. In response ae Spamcop admins posted:
SpamCop does not block ANY email at all that is sent to spam.spamcop.net addresses. We do not use our own blocking list. We might bounce emails to certain addresses, but we do not block anything that comes our way.
The same applies for the SpamCop Email Service. However, they do use greylisting, which delays acceptance from some servers until the server tries again. Continuing to try to deliver email is standard behavior for legitimate mail servers, but not for spammer servers, which only try once and give up.
I suppose it is possible that Apple is seeing the greylisting delay when they try to send mail to spamcop.net, cqmail.net, or cesmail.net addresses and thinks it is a rejection.
If the problem really is forwarding spam to the Spamcop reporting address, it could be Apple filtering outgoing mail to prevent spam from leaking out their servers. If the problem really is sending mail to Spamcop.net addresses it could be a bad interaction between MobileMe and Spamcop’s greylisting scheme. Without seeing the actual transactions between the two servers it is difficult to determine what is happening.
In any case, this demonstrates some of the challenges involved in troubleshooting mail problems. People are poking the system from the outside, but there seems to be some one along the line silently discarding email, leaving senders (and receivers!) in the dark about where the email went.