SMTP (Simple Mail Transfer Protocol) is a protocol used for sending email messages between servers. It is the standard protocol for sending email messages over the Internet.
SMTP works by enabling a mail server to send emails to another mail server. When you send an email from your email client (such as Outlook or Gmail), your email client uses SMTP to communicate with your email server (SMTP server) and send the email to the recipient’s email server.
SMTP operates on port 25 by default, but secure variants such as SMTPS (SMTP Secure) and STARTTLS (SMTP with TLS) are also used to encrypt the communication between servers, preventing unauthorized access to email content.
Example (SMTP Process):
- You compose an email in your email client and click “Send”.
- Your email client communicates with your email server using SMTP to send the email.
- Your email server contacts the recipient’s email server using SMTP and delivers the email to the recipient’s inbox.