We sent out two rejections the other day that got bounce messages from a server between us and the intended recipient, telling us that our server was blocked by Barracuda Reputation.
I followed the URL, and learned that an antispam service called Barracuda Central had decided that our mail server had a "poor" reputation and was thus probably a spam server. So they're blocking all mail from that IP address.
We're using a mail server owned by Pair.com, a major web hosting company. It's certainly possible that someone else who uses that server sent out some spam—but based on past experience, it seems more likely to me that some Pair customer once again got confused about where some spam was coming from, and misreported it as coming from a Pair server.
Fortunately, this only happens once every year or two. But every time it happens, it reminds me one more time why I don't trust spam blacklisting organizations.
I'm glad to see that Barracuda automatically resets the reputation score to normal for a believed spammer for 48 hours after a request, while they investigate. So now that I've requested removal, we can re-send our rejection, and chances are it'll go through.
Still, let this be another reminder to authors (and everyone else): if you don't receive a piece of email that you were expecting, it's entirely possible that the senders sent it but that some server somewhere along the way decided not to let you see it. So if you don't receive an expected piece of email in the expected time period, drop the sender a note to check on things.
PS: There's a big green box at the bottom of the Barracuda page that says:
One way to avoid having your email inadvertently blocked is by registering your domain and IP addresses at EmailReg.org. Emails from domain names and IP addresses that are properly registered on EmailReg.org can be automatically exempted from spam filtering defense layers on Barracuda Spam Firewalls and other anti-spam solutions, preventing your email from being accidentally blocked.
So I followed the link. Turns out EmailReg.org costs $20 to register your domain; what's more, they have an explicit post explaining that registering with them won't help with Barracuda:
There appears to be some confusion that EMAILREG.ORG is a way to get off of some of the Barracuda IP Block lists (BRBL). This is not the case. Emailreg.org is primarily a whitelist of IP's with domains. It does not have any impact on Barracuda Networks block lists such as the BRBL. If you want to be delisted from a Barracuda Block List please contact Barracuda Networks at their technical site: www.barracudacentral.org
I'm guessing that the reason "there appears to be some confusion" is that the Barracuda page itself strongly implies that it's true. Get your story straight, people!
Can't say I'm impressed with either of these organizations from what I've seen so far. But I don't know anything about either of them beyond what I saw tonight, when I was predisposed to be annoyed by them, so for all I know they may be great organizations doing wonderful work.