There’s currently not a programmatic way to make those determinations, but this is where the relationship between senders and receivers comes in. All you have to do is ask recipients what they want. I know, I know, most marketers have a low opinion of the ability or desire of their recipients to respond to an email. And there are some actual challenges to getting a recipient’s attention when they’ve tuned out a particular sender or type of email.
Separating out zombie addresses from real addresses is a challenge. But it’s part of maintaining a healthy email marketing program. When I’m working with clients who are mailing old lists we first talk about their product and their goals. Then we look at what information they have for recipients. My goal is to separate out those addresses we know are good from those we know are bad from those we don’t know. It’s the ones in the don’t know category that we focus on.
I don’t recommend just deleting the addresses that are non-responsive. One of the reasons is that I read mail with images off by default and so I often look like one of those non-responsive recipients even when I’m actively reading and receiving mail. Instead, I like to look at what other data the customer has about a recipient to help classify them. Of course, there are often a subset of users we cannot identify if they’re zombies or not. For these addresses we plan a re-engagement campaign.
Clients who have gone through this process have seen an improvement in delivery and an improvement in responses and ROI.
Until and unless ISPs start rejecting mail for zombie accounts it’s the best chance senders have to separate the barely there from the not there at all.