Jul 2, 2007

Postini Likes DKIM Authentication

We’ve posted in the past how frustrating it can be to get legit email campaigns past the Postini firewall (see: Getting Blocked by Postini?). It just seemed very random how they filter emails. Why do some emails get through, and some don’t?

We think we just stumbled upon the answer.

We’d recently been testing some DKIM authenticated MailChimp campaigns with our Inbox
, just to see how things rendered. We were putting in
gobbledy-gook placeholder text. I mean, sloppy junk that would normally
get you spam filtered in a heartbeat. Our test campaigns were also very image-heavy, which is known to trigger spam filters. Here’s a screenshot of how our test email looked in Outlook (just so you get an idea of how truly bad our test email was):


Lo and behold, they all got past Postini with flying colors.


Normally, you’d want way more text in the message to "balance out" the big header graphic. It also helps if you don’t use a bunch of random junk text. But DKIM authentication seemed to tip the scales and got our message through.

We still scored high on the content filters (2.0 Spam Assassin Score), so I’m sure that without a properly configured email server, even DKIM wouldn’t be a silver bullet to get past Postini. But boy, it sure seems to help.

An interesting side note: In addition to the fact that our email was too image-heavy, almost every spam filter penalized us for having "fda" in our email (as in, "This drug has been approved by the FDA to enlarge…"). One more example how "every word in the English dictionary is now a spam word" (as someone at ReturnPath told us recently) and how you need to be careful if you’re sending test campaigns with placeholder text in it.

MailChimp users, you will soon have the option of adding DKIM authentication to your accounts with the click of a button. Look for an announcement soon.

Learn more about our Inbox Inspector add-on

Learn more about DKIM authentication