Just like most of you, we send out thousands on opt-in emails each day to job seekers that have requested jobs, and companies that have requested resumes. We have been working on the best way to clean up our lists to get rid of bad email addresses, without getting rid of valid addresses where a mail box is full, or where the email was blocked due to Spam filtering. We have done this one way in the past, but we are looking for a fresh and better approach. Any ideas would be greatly appreciated.