Most Auto Responders do not allow you to upload lists of Emails, for good reasons.When an email message cannot be delivered to an email address, it’s called a bounce. The ones that do penalize you if your list contains too many emails that bounce.
There are lots of different reasons why emails are not delivered. No more nasty notes from your Auto Responder provider. No more ISPs blacklisting you for mailing bad or ghost addresses. Clean that list.