Live Email Verifier is a lite tool which will do it for you. You only ave to insert the e-mail addresses and Live eMail Verifier will tell you if they are correct or not.
You can import the mail list or add them manually, then let Live eMail Verifier do it for you. It's fast and accurate and you'll know if the addresses you have in your mailing list are OK.
-It uses the Port 25, so it should be open.-It supports all Windows OS.
The trial version only checks a limited number of e-mail addresses.