Campaign Monitor has an interview with Gmail looking at how to get mail to the Gmail inbox. It’s a great article and I think everyone should go read it.
One of the most important things it talks about is how complex filters are.

On Gmail’s end, Sri revealed that there are literally hundreds of signals to decide whether an email should go to the Inbox or the Spam folder. The importance of any given signal is dynamic and determined on complex algorithms, in essence it means that one factor or another isn’t likely to bin an entire campaign and there is no point in obsessing over any one element. “Think of how you can make the user love your mails rather than how to land in the Inbox” was Sri’s basic advice on the subject. Essentially stating if the user likes your mail the spam filter should not stop it from getting to the Inbox.

This really is the crux of delivery. Send email users want to receive. Sri’s statements to Andrew echo many of the things he, and his team, shared with us at M³AAWG in February. I focused more on the technical things but engagement and mail users want to receive was an ongoing theme through the talk.
Gmail is often the toughest inbox to crack because they rely so heavily on engagement metrics. But engagement as a metric for delivery is nothing new. I’ve been writing about how engagement is critical for delivery since at least 2008. I have posts from 2011 talking about how to increase engagement and inbox delivery.
I know that engagement and relevance are bad words in the marketing space. An number of marketers have made very public statements about how relevance is dead and engagement is something bad consultants have made up to keep them in business. The fact of the matter is that engagement is something the ISPs do look at and do measure. Anyone who wants to have a successful email marketing program needs to look at what their users want to receive. Sending mail users want leads to inbox delivery because that’s what makes the ISPs money.

engagement • gmail