I think that Dreamhost has to be proactive in that way. You have to implement ways to make sure that your clients are not spammers. Waiting for others to tell you that is kind of too late. It’s a good check on your system, but it’s only after the fact.

PREVENT!

Razor is gone.
The new “Junk” email stuff seems to be this new anti-spam effort.

One think though, the new “Junk” email stuff is not permitted on accounts that have the “catch-all” ability / account enabled.

Because they catch “lots” of junk email.
Well.
Isn’t that a *highly* useful category to have?
If only as a predictive / confirmatory indicator / telltale?

Further, what about deliberate “HoneyPot” domains?
Domains that have no purpose in life except to collect unsolicitied email?
Virtually all email they would receive, other than from their registrar / web email host?) would almost certainly be spam.
Similarly, “HoneyPot” email links posted on the web, deliberately placed / enabled for web-bot email harvesters to collect?

Shutting off IP addresses from the email world for 4 hours or so at a whack is going to be uncomfortable, most especially if there isn’t some sort of “spam hold” type of status for users to become familiar with.

Now, you want good spam blocking, go to Gmail! If I happen to get a lot of spam, in a week or so, they’ve figured out how to block it all and send it ALL to the spam folder. I rarely get spam. When I do, it’s new and persistant, but like I said, gets completely blocked with time.

There would definitely be technical hurdles to prevent issues like what you described. The bigger hurdle would be actually convincing all of the big email providers to play nice together and go along with something like this, though. But anyway, to try to reduce the potential for exploit you could do some sort of cross-checking on reported spam and only consider it spam if it’s reported by more than one outside email provider and then only start blocking email once a specific spam is reported X number of times and that X could be separately adjusted for each provider reporting spam to balance out the reliability of their own systems.

It seems like most of the proposals I’ve seen to reduce spam focus on reducing spam coming into a network and there doesn’t seem to be all that much focus on network companies working together to reduce the spam at the source networks themselves. I’d like to see more companies take more responsibility for that.