SMTP, or Simple Mail Transfer Protocol, is the standard protocol for sending emails across the Internet. It is a crucial part of the email delivery system, enabling the transmission of messages from a sender’s mail server to the recipient’s mail server. SMTP operates on a client-server model and typically uses port 25, although ports 587 and 465 are also commonly used for secure transmission.
How SMTP Works
- Email Composition: The user composes an email using an email client (e.g., Outlook, Gmail).
- SMTP Client: The email client acts as an SMTP client and connects to the SMTP server to send the email.
- Connection Establishment: The SMTP client establishes a connection with the SMTP server using the appropriate port (usually 25, 587, or 465).
- Mail Transfer: The SMTP client sends the email data to the SMTP server, which processes and forwards the message to the recipient’s SMTP server.
- Recipient Server: The recipient’s SMTP server receives the email and stores it in the recipient’s mailbox.
- Email Retrieval: The recipient retrieves the email using a mail retrieval protocol like POP3, IMAP, or by accessing it directly through a webmail interface.
