service to find and delete contacts/email addresses that are bad (undeliverable, spam traps, etc.) like a number of other services do.
Great news! We recently released this feature. Please see our blog for more information:
Joseph Little commented
If you get into email validation, it is tricky. Thus, I do NOT recommend that you delete the seemingly 'dead' email address. But you mark it with a status (maybe: clearly good, probably good, probably bad, very likely bad). For the 'very likely bad' ones, I would be ok if you move them to Notes, such as "VL Bad: firstname.lastname@example.org"
That way we can review your changes and decide what to do with them.
False positives or negatives seems very likely to me in this area.