[byoung2]

You might be listed in a blacklist provider such as Spamhaus. Try your server's IP and hostname at http://www.spamhaus.org/lookup/. If it is just an IP that's blocked, it may be quicker to get a new IP address from your hosting provider.

[Duhveed]

No, I'm not listed in the spamhaus lookup and I checked another list that microsoft indicated they made use of on one of their so-you've-been-blocked pages and I wasn't on that either. Best I can tell, it's just MS that has an issue with it.

I'm starting to agree that it's likely quicker to get a new ip address, but I hate that that's where I'm at. I wholly admit that I as the admin of the server should've caught it before I got blocked, but there's an admin (or more likely, a team of them) at MS who's just as asleep at the wheel as I am.

[nodata]

Check here: http://www.dnsbl.info/dnsbl-list.php

[Duhveed]

I'm all-clear on all of those. Great site, btw.