Gmail suddenly puts mail in the bulk folder

One of the delivery challenges that regularly comes up in various delivery discussion spaces is the “Gmail suddenly put my mail in spam.” From my perspective, there is rarely a “suddenly” about Gmail’s decision making process.

As I was answering one of these questions I had a number of thoughts. I’ll share them here on the blog so I can find them in the future.

The first thing that occurred was that I’d shifted my thinking to considering Gmail filtering, in particular, as a filter based on a mailstream, not on a message. Thus my tweet:

The other was a realization that most people don’t consider how what they’re doing might be not OK, but might not be bad enough to be filtered this time. That not OK behaviour builds up over time and eventually tips into mail being filtered. Not because of one message, but because of the dozen or 40 or 75 or hundred messages behind it.

Gmail is really good about just watching and monitoring and watching and scoring. They measure mainstreams over time, and reputation is the sum of all your sends. There may be nothing different or new about a particular send, but Gmail’s been seeing overall reputation decrease just a little bit every time you send.

To put it more succinctly: Senders see themselves “doing the same things” and not realising that every time they do this, they’re slowly eroding away at their reputation with Gmail. Once the erosion hits the tipping point

As I explained it on Facebook.

The effect (moving mail to spam) happens suddenly. The cause builds up over time. Gmail is really good about just watching and monitoring and watching and scoring. They measure mainstreams over time, they don’t really measure individual sends.

What happens is that Gmail starts moving mail sent to people who don’t engage with it to the bulk folder. Your open rates don’t change because these people aren’t opening the mail anyway. But every message delivered to the bulk folder is a ding on your reputation. Those dings build up, until your reputation hits a tipping point and all mail to some of your engaged users sometimes goes to bulk. You might see a small decrease in open rates, but nothing major. You continue mailing as you are and then “all of a sudden” your mail is going to bulk. But it’s just mail to the people who were receiving it in the inbox before, the majority of your mail was always going to bulk. 

This is why any changes you might make to mail, changing an IP or a domain name or using a slightly different format, can sometimes work for a little while. It’s basically decoupling that individual message from the broader history of sending. So you can keep doing the same things over and over again and not hit the inbox.

If, however, you don’t fix the underlying problem, one of two things will happen. Google will connect the new mailstream with the old mailstream and your reputation will fall to the old reputation in a few days. Alternatively, Google won’t connect the new mailstream with the old mailstream and you’ll have many months to slowly erode the reset reputation. In either case it’s just a matter of time before you end up back in the bulk folder again.

Gmail looks at the whole message stream when making decisions. In order to improve delivery at gmail we must also look at the whole message stream.