There’s a terrific piece at the MailUp Blog that describes a recent panel of the Big Four free inbox providers at the EEC meeting this week. It confirms what deliverability folks have been trying to communicate to their clients for a couple of years now. While the message may not be a new one, it carries far more weight to hear it directly from the horses’ mouths, so to speak.

The short version: email deliverability is more personalized than it has ever been, and will likely continue to become more so. What is relevant to one recipient may be junk to another. Big ISPs can and do measure individual recipient interaction and engagement with messages, and use that data to inform automated deliverability decisions for individual recipients.

So what kind of data or signals are the Big Four looking at? Here’s what they had to say at the EEC panel:

These seven signals of inbox engagement play a fundamental part in determining the relevancy of your email campaigns for a specific recipient.

1. Open (GOOD): although they know that open has become a less relevant metric (images downloaded by default in certain email clients), they still track it
2. Reply (GOOD): a reply to a message is considered a super-strong signal of engagement. If you ever needed evidence that using a “no-reply@…” email address is a bad idea… here we go!
3. Move to junk (BAD): strong, negative signal. Two of these on AOL are enough to automatically place that message in the spam folder from then on, for that recipient.
4. Not junk (GOOD): strong, positive signal that the message should not be considered spam.One of these on AOL is enough to “reset” the previous behavior.
5. Delete without open (BAD): a quick glance at the sender/subject, and they didn’t like it: a negative signal.
6. Move to folder (GOOD): if you are moving certain messages around, it means you care about them.
7. Add to address book (GOOD): it shows that the sender matters to the recipient.

In the case of Outlook.com, only number three – flagging a message as spam – hurts the overall sender reputation. The rest affects inbox personalization (whether a message ends up in the inbox for a specific recipient), but not overall reputation. For the other three, all signals affect both reputation and individual personalization.

Does this mean that IP or domain reputation don’t matter anymore? No, it assuredly doesn’t. The panel was clear that these are still important signals that play a role at SMTP time, and of course they matter even more at other recipient domains that aren’t GAMY.

What it does mean (and stop me if you’ve heard this before) is that senders have far more control over and responsibility for the success of their own messaging programs than they typically understand. The full text of the article appears here.