What is SMTP?
Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email) transmission. Electronic mail servers and other mail transfer agents use SMTP to send and receive mail messages, user-level client mail applications typically use SMTP only for sending messages to a mail server for relaying. For retrieving messages, client applications usually use either IMAP or POP3.
You can select an email address (like Gmail and Yahoo mail) as client and use the SMTP service. Ursalink routers can then use the email address to send alerts.