Security Monitor Pro is compatible with almost every email server. Please check your entries for the SMTP server, your username and password to make sure they are entered correctly. SSL security will not work with port 25. If you have to use port 25, you can try no security. If you would like to use SSL security to send your email, change the port number to 465. Make sure you set security to SSL (not TLS). SSL encrypted SMTP uses port 465.