I cannot stress the importance of our contact list. Your software has incorrectly flagged email addresses as BAD.

After exporting the BAD results to my sales team, I was informed that one of the addresses was indeed a good address.

So, taking the exported BAD list, I rescanned all the addresses. Over 100 contacts that were previously flagged as BAD, were now be validated as being GOOD. How embarrassing.

I cannot believe that I recommended that my sales team remove these contacts from their database. This could have resulted in lost sales to our company.

What could be the explanation of these results?

Look at the log of that testing process. The response is there. The log has all the responses from the servers. eMail Verifier doesn't mark emails on its own, it waits for the server response and mark the address accordingly.