My buddy and I were just chatting tonight about spam blacklists and how hard it is to navigate even when you know what you're doing. He manages his own email server and subscribes to one of the less extortionate blacklists (there are many spam blacklists out there, and some are more reliable than others) and this week he got a call from his insurance agent asking whether he had the information ready to send over that the agent had asked for in his last email. Turns out that while the agency's automatic mass email stuff was getting through just fine, his agent was sending from home or some such thing, via an outgoing server shared with a lot of other customers ... and when one of the 1000+ other people using that server gets compromised and starts sending out spam, then everything sent via that outgoing server is suspect. And it had got onto the blacklist, badly enough that my buddy's mail server wasn't just dropping it in the spam bucket, it was just kinda dropping it without acknowledgment. He would have never known if the agent hadn't called, because other email from the same domain (but being sent via a different mail server) was getting through. Best of luck if you do wind up managing your own server! I salute everyone who makes the attempt, because the world needs people willing to make a go of it to see if they can.

Longevity doesn't necessarily mean that much when there's been a sudden change in pattern, since there's always the chance that a spammer compromised a legitimate provider and is now attempting to fire the spam-cannon double-quick before they get shut down and have to compromise someone else's mail server. I suspect that the bigger the provider, the less they care about individual email getting through as long as they can lower their spam volume and reduce their hours of labor to email traffic ratio. :\