1st Email Address Verifier 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 the sending of message. It does not come to the message sending it disconnects as soon as mail server informs does this address exist or not. EAV can find about 90% of dead addresses - some mail systems receive all messages and only then see their addresses and if the address is dead send the message back with remark about it. 1st Email Address Verifier can save time and money for businesses that send newsletters to their clients, nonprofits who send bulletins to their members, or any person or business that needs to maintain a clean e-mail contact list.