From 101 Internet Marketing Software:
101 Email Address Extractor is a software designed to directly search email addresses from mail servers. It can verify all user names that you specified on the mail server.The program tries to connect with a specail SMTP server and simulates sending the message. It does not come to the message sending, in fact, it disconnect as soon as mail server informs that this address exist or not.The program is multi-threaded that provides the high speed of verifying and allows to regulate the network traffic and your machine loading. Using this software, you can get lots of email addresses from any email server, such as hotmail.com, aol.com etc on the fly.