Filtering secret sauce

It seems one of the most asked questions I hear from people is about filters and what the secret sauce is.

Cloudmark’s processes which determine which IPs get a poor or suspect reputation in our CSI products, take into account many different factors, including both spam trap hits and volume of trusted end user complaints (hitting the “This is spam” button), reputation of the reverse DNS of the IP, reputation of the IP block that the IP is part of, and traffic volumes over time which help measure likely use of the IP in a snowshoe attack.
ISPs primarily want their email infrastructure to stay available and performing well, and for email recipients to receive the email that they want to receive. But if as a sender or marketer your email is going to spamtraps or people are hitting the “This is spam” button, then it’s not going to people who want it. Email blacklists and Cloudmark’s Sender Intelligence

Cloudmark is saying all the things deliverability experts tell senders. Maybe hearing it direct from the source will make the message stick better.

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IP reputation and email delivery

IP reputation is a measure of how much wanted mail a particular IP address sends.  This wanted mail is measured as a portion of the total email sent from that IP. Initially IP reputation was really the be all and end all of reputation, there was no real good way to authenticate a domain or a from address. Many ISPs built complex IP reputation models to evaluate mail based on the IP that sent the mail.
These IP reputation models were the best we had, but there were a lot of ways for spammers to game the system. Some spammers would create lots of accounts at ISPs and use them to open and interact with mail. Other spammers would trickle their mail out over hundreds or thousands of IPs in the hopes of diluting the badness enough to get to the inbox. Through it all they kept trying to get mail out through reputable ESPs, either by posing as legitimate customers or compromising servers.
These things worked for a while, but the ISPs started looking harder at the recipient pool in order to figure out if the interactions were real or not. They started looking at the total amount of identical mail coming from multiple IP addresses. The ISPs couldn’t rely on IP reputation so they started to dig down and get into content based filtering.
As the ISPs got better at identifying content and filtering on factors other than source IP, the importance of the IP address on inbox delivery changed. No longer was it good enough to have a high reputation IP sending mail.
These days your IP reputation dictates how fast you can send mail to a particular ISP. But a high reputation IP isn’t sufficient to get all the mail in the inbox. It’s really content that drives the inbox / bulk folder decisions these days.
 
Generally IPs that the ISP has not seen email traffic from before start out with a slight negative reputation. This is because most new IPs are actually infected machines. The negative reputation translates to rate limiting. The rate limiting minimizes people getting spam while the ISP works out if this is a real sender or a spammer.
Some ISPs put mail in the inbox and bulk foldering during the whitelisting process. In this case what they’re doing is seeing if your recipients care enough about your mail to look for it in the bulk folder. If they do, and they mark the mail as “not spam” then this feeds back to the sender reputation and the IP reputation.
If you’re seeing a lot of bulk foldering of mail, it’s unlikely there’s anything IP reputation based to do. Instead of worrying about IP reputation, focus instead on the content of the mail and see what you may need to do to improve the reputation of the domains and URLs (or landing pages) in the emails.

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Cloudmark posted their Global Spam Threat Report for 2013.

Cloudmark Annual Global Messaging Threat Report. Nothing too surprising here, but useful for anyone in the email space to check out.

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Thoughts on Gmail and the inbox

Over the last few months more and more marketers are finding their primary delivery challenge is the Gmail inbox. I’ve been thinking about why Gmail might be such a challenge for marketers. Certainly I have gotten a lot of calls from people struggling to figure out how to get into the Gmail inbox. I’ve also seen aggressive domain based filtering from Gmail, where any mention of a particular domain results in mail going to the bulk folder.
It’s one of those things that’s a challenge, because in most of these cases there isn’t one cause for bulk foldering. Instead there’s a whole host of things that are individually very small but taken together convince Gmail that the mail doesn’t need to be in the inbox.
A pattern that I’m starting to see is that Gmail is taking a more holistic look at all the mail from a sender. If the mail is connected to an organization, all that mail is measured as part of their delivery decision making. This is hurting some ESPs and bulk senders. I’ve had multiple ESPs contact me in the last 6 months looking for help because all their customer emails are going to bulk folder.
Gmail’s filtering is extremely aggressive. From my perspective it always has been. I did get an invite for a Gmail account way back in the day. I moved a couple mailing lists over to that account to test it with some volume and discussion lists. I gave up not long after because no matter what I did I couldn’t get gmail to put all the mail from that list into the tag I had set up for it. Inevitably some mail from some certain people would end up in my spam folder.
Gmail has gotten better, now they will let you override their filters but give you a big warning that the message would have been delivered to spam otherwise.
Gmail_NotSpam
What are mailers to do? Right now I don’t have a good answer. Sending mail people want is still good advice for individual senders. But I am not sure what can be done about this ESP wide filtering that I’m starting to see. It’s possible Gmail is monitoring all the mail from a particular sender or ESP and applying a “source network” score. Networks letting customers send mail Gmail doesn’t like (such as affiliate mail or payday mail, things they mentioned specifically at M3AAWG) are having all their customers affected.
I suspect this means that ESPs seeing problems across their customer base are going to have to work harder to police their customers and remove problematic mail streams completely. Hopefully, ESPs that can get on the Gmail FBL can identify the problem customers faster before those customers tank mail for all their senders.

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