From what I've seen and been reading, it seems that there is not a way to configure spamcop to automatically delete held mail after x days, truly automatically, with no intervention (i.e. logging into webmail) on my part. So, assuming this to be the case, should I care? If I just use spamcop to filter and forward, it really won't matter to me if there are nine million held messages attached to my account. I've made the decision that I'd rather miss an e-mail here and there than have to go through all the spam I get to look for false positives, so I have no intention of ever looking at my held mail.
But, this being said, I don't want to rudely take up space on spamcop's server with my spam when it's totally unnecessary. But, if they don't give an option for this not to happen, well, I guess there's nothing I can do. So, let's say I get about 3,000 spams/week and I use spamcop over the next year. Spamcop will wind up with 156,000 messages on their server that I don't have any intentions to ever look at?
I realize that it's not a big deal to log in, delete the messages, and all that. But this doesn't fit the solution that I'm after and I'll go with something else (i.e. gmail) for filtering if I "have to" do this.