Multiple lists have been discussing DNS failures for URIBL.com over the last few hours. This is causing some serious mail problems for folks, both on the inbound and the outbound.
URIBL has a note on their home page (which is unreachable for some folks).
June 4th, 2013: DNS Issues
Our top-level domain that handles DNS resolution for serveral of our services is currently in LA-LA-LAND with Godaddy. We dont know why, and they cant tell us why. We’ve switched over to new nameservers until Godaddy has resolved whatever they’ve effed up. Any remaining issues at this point are just due to waiting on DNS cache expiry to occur.
If you’re using URIBL, you’ll want to manually clear your DNS cache. If, for some reason, you can’t manually purge your cache, you can disable URIBL lookups until the old listings expire.