MDaemon IMAP, SMTP, POP3 Windows mail server software
CommuniCrypt Mail Standalone POP3/SMTP eMail client with built-in strongest asymmetric Public-Key-Encryption with RSA encryption algorithm (RSAES-OAEP).Key length for encrypting up to 7120 bit.
SMTPDiagPro SMTPDiagPro is a small tool to test the configuration of a SMTP-Server including DNS MX, blacklisting and open relay