There are a few different ways of getting this information… A good way to get a good picture of what is happening with your list is to look at the bounces (emails that are not making it to the person’s inbox). For more info about what bounces are and the difference between hard and soft bounces, click here.
To view the bounces for all e-newsletters or a specific e-newsletter, in the EMS system go to: Reports > View Bounces.
In the example above, you can see that the email email@example.com bounced because there is no such user. “Filtering by Campaign” will give you the info per e-newsletter. This information is also given in aggregate form on the Executive Report.
For most accounts, bounced emails are deleted after 4 hard bounced emails. This is for list cleaning purposes so that your list doesn’t house emails that are obviously not making it to the recipient and so email systems don’t start blocking your emails because you have too many dead subscribers.