From my working life....

Trouble with Comcast? You’re Not Alone
Feb 5, 2008 2:30 PM , By Ken Magill

Dave Linhardt isn’t the only e-mailer apparently having trouble with Comcast.

The chief executive of e-mail marketing firm e360 Insight sued Comcast recently, claiming the cable and Internet service provider was blocking his e-mails from reaching recipients.

It turns out Comcast is blocking a lot of senders’ e-mail, according to multiple sources.

Comcast, however, begs to differ.

Multiple e-mail deliverability specialists are reporting that many of their clients are having difficulty getting their e-mail into Comcast address holders’ inboxes.

“I can usually tell when one of the ISPs makes some change to their incoming spam filtering just by my call volume,” wrote co-founder of deliverability consultancy Word to the Wise, Laura Atkins, on her blog. “The past few weeks, the ISP in most of my calls has been Comcast. And, what do you know, they have made changes to how they are filtering e-mail.”

This is not a small problem. Comcast is the No. 2 Internet service provider with 12.9 million subscribers, according to ISP Planet.

Comcast recently began using technology from anti spam firm Cloudmark. The change apparently resulted in heavier filtering of incoming e-mail.

Also, Comcast has been fiddling with its throttling rules resulting in fluctuations in the amount of e-mail it will accept from mailers, according to Len Shneyder, director of partner relations for deliverability consultancy Pivotal Veracity. Comcast has also limiting the number of connections any sender can establish with its servers.

As a result, e-mail is getting into Comcast more slowly.

“In general, the entire industry is experiencing problems with Comcast due to heavier filtering and rate limiting,” Shneyder said. “This is not unusual for ISPs in their fight against spam as they fine tune their systems to cope with the ever-increasing volume of spam.”

What to do? Shneyder recommends throttling, or slowing the amount of e-mail sent to Comcast addresses. He adds this may be difficult for some mailers with internal e-mail or home-grown systems, but most e-mail service providers can throttle e-mail by domain.

Shneyder said his contact at Comcast told him last week that mailers should limit outbound messages to Comcast addresses to six recipients per second.

Shneyder also said his Comcast contact told him senders should limit their connections to its servers to 10 per IP address.

Meanwhile, Jay Opperman, director of security and privacy for Comcast, said he isn’t aware of any widespread deliverability issues affecting incoming permission-based e-mail at the cable provider.

“The way I tell if it’s a big broad problem is I’ll get escalations, and we’re not seeing that,” he said. “Metrics that I have say we’re getting to the phone and answering people’s phone calls.”

He confirmed that Comcast implemented new anti-spam measures at the end of the third quarter of last year, including switching from anti-spam technology provider Brightmail to Cloudmark.

Opperman added that like many ISPs, Comcast places great weight on spam complaints from subscribers when determining how to handle incoming mail.

“Principally, a lot of actions that we take are based on feedback from our customers,” he said. “The issue that we run into with most of e-marketers is they don’t have a clean list.”

Opperman also said Comcast is considering increasingly using mailers’ so-called reputations—generally defined as the number of spam complaints a mailer gets, and the number of dead addresses and spam complaints a mailer hits—to determine how to process incoming mail.

“We’re looking at it,” he said. “We have not implemented a reputation-based filtering system at this point.”

Opperman added that when Comcast blocks a sender’s mail, the mailer will get an error message with a code and links they can follow for instructions on how to solve the problem. Mailers who experience deliverability issues should follow the links and fill out the appropriate forms when the situation warrants. They can also call Comcast’s anti-spam team, he said. The number is (888) 565-4329.

“If they don’t feel that their problem is being addressed, they can always escalate,” he added.