A simple protocol for the transmission of mail (SMTP), used to communicate with the remote server and subsequently send messages from the local client to the remote server, and ultimately to the recipient's server. On your email server, this process is controlled by a special service (MTAIt is worth mentioning that SMTP is used exclusively for sending messages.
SMTP ports:
- Port 25 – an unencrypted port
- Port 465 – an SSL/TLS port, also known as SMTPS