Hello @PaulK91 ,
In order to protect the delivery rate of both Constant Contact and our customers, there are certain types of email addresses that we do not send to. Among them are email addresses that continually bounce as Non-existent. Since repeatedly sending emails to "Non-existent" addresses can have a negative impact on sending reputation, Constant Contact suppresses these addresses and marks them as "Suspended" in your email reporting.
You can attempt unsuspensions in your account for contacts bouncing as suspended. You can also respond to the @ mention email you automatically receive from my reply, or call our general support, to have us attempt an administrative unsuspend of the contacts. If you're needing more than 15 contacts unsuspended, we ask that you call our Deliverability team so they can investigate why so many legitimate email addresses were bouncing as non-existent enough for our system to suspend them.