Occasionally? Apparently you either:
A. Are a spammer, or
B. Are completely clueless
VPS is rapidly becoming *the* most popular hosting method used by non bot herder spammers.
Or C. Neither. Thanks for assuming I don't know what I'm doing.
I'm referring to Linode.com. It's possible that it's getting abused by spammers occasionally, but I'm not aware of such complaints, it's a relatively small operation, and the staff seems pretty on-the-ball. The times that UCE-protect has added us to their blacklist that I'm aware of, it has been entirely due to IPs outside the Linode ranges as far as I could tell (which is supported by their arguments on the forum). I could be wrong, of course.
Whether it's a fair world or not, blacklisting entire blocks and not just the bot-infected or spammer hosts does more harm than good, especially when you're talking about blocking entire netblocks that cross multiple businesses full of non-spammer customers.
I am a mail admin, and I'm aware of VPS reputation, but that's not what this is about. I wouldn't use UCE-protect because I see it as nothing but a source of false-positives. Stopping spam is an important service to your users, but getting their legit mail through is more important.
Full STOP yourself.