Just woke up this morning and thought I'd get working on tool I'm creating to be able to monitor if and when we get put onto blacklists, when lo and behold, I discover our default ip is again on the cbl blacklist. A couple of hours of diagnosing and debugging later and I've found that our hosting provider as a part of their recent upgrades decided to go and change our hostname settings on our MTA, causing everything to come off of 'localhost.localdomain'. Wonderful. As if we didn't have enough problems, now we've got a MTA that's misconfigured and for the changes to take effect it needs a nice reboot. Well, luckily the reboot went well and our MTA is again sending happily off of a proper hostname.