Comcast blocks outgoing email based on content
Know that Comcast denies this, but it’s true. If Comcast is your ISP, their new email system is reading your outgoing mail and deciding which of your messages are acceptable to send.
Comcast recently consolidated its mail operations to a center in Pennsylvania, near its Philadelphia headquarters. You may have noticed, in late October and early November, that you were getting frequent error messages when sending mail. That was a load-balancing problem on the new servers that Comcast seems to have resolved fairly well.
The new Web interface is called SmartZone, and Comcast really really wants its customers to use that interface for sending and receiving mail, despite its many usability shortcomings. (Hint to Comcast subscribers: If you haven’t logged into the SmartZone interface, do so. You may find mail in your spam folder that isn’t spam. No, you cannot turn off the built-in spam filtering, despite the controls that say you can. This is a known issue. It’s unclear whether they’re working on fixing it.)
But whether you use the SmartZone interface or prefer, as I do, a traditional POP mail client like Mozilla Thunderbird, as a Comcast subscriber, you send your outgoing mail through their server (smtp.comcast.net), even if your return address is some other domain you control.
So here’s what happens: If the message body of your outgoing message contains a forbidden string of characters, the message disappears. You do not get an error message saying it could not be sent. You do not get a bounceback message from the server saying it was blocked. It just disappears. In my case, the exact content of the forbidden string has varied somewhat. Initially, it was the full URL of this blog, http://ampersandvirgule.blogspot.com/, but if I left off the http:// part, the message went out. Then it was either version, but other blogspot addresses were okay. In testing yesterday, all it took was “.blogspot.com” by itself to cause the message to fail.
Throughout these tribulations over the last month or so, Comcast engineers have repeatedly sworn to me that they do not filter outgoing message content and that what I reported to them is impossible. I’m sure they thought they were speaking truthfully, but the facts stood in opposition.
In the last go-round, yesterday, after I called the office set up at corporate headquarters to handle irate customers (that would be me)—which you can reach by asking for the president’s office at 215-665-1700—all of my blocked test messages from earlier in the day suddenly appeared in my inbox. When I called back today to ask whether anyone had noted in the case file what they had actually done to solve the problem, the customer service rep said no. The only note was that someone (unsigned) had “temporarily” fixed the problem but that it would return. There was no indication of what the temporary fix actually was.
Now I cannot pretend to know whether this problem affects other accounts besides mine or whether the forbidden string is the same for everyone. All I know is that you should do your own testing, check your SmartZone spam folder regularly, and BCC yourself on every message that goes out through Comcast’s servers.
I’d rail about free speech and invasion of privacy, but as whatever is happening seems to be mediated by some daemon that nobody at Comcast believes exists, it hardly seems intentional. Maybe this is the hand of Homeland Security at work, and it’s beyond Comcast’s control. Maybe it’s just a random artifact of the complexity of modern software. I’m unhappy about it, and I’m complaining about it, but I’ll leave the First Amendment issues for another day. I’m not even going to piss and moan about the travesty that passes for customer service at Comcast. That can wait, too. I mostly just wanted to alert Comcast subscribers to keep track of your email and not assume that it’s all getting through—in either direction.