1st Email Address Verifier (EAV) is a program that verifies the validity of e-mail addresses in mailing lists.The program works on the same algorithm as ISP mail systems do. Mail servers addresses for specified address are extracted from DNS. The program tries to connect with found SMTP-servers and simulates sending a message, but does not send the message out. EAV disconnects as soon as mail server informs whether this address exist or not.