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What is SMTP (Simple Mail Transfer Protocol)?

What is SMTP and why is it important?

What is SMTP?

SMTP is a protocol used in sending and receiving emails, it is today completed with POP3 (Post Office Protocol) and IMAP (Internet Message Access Protocol) on the receiving part.

SMTP is a three-steps process:

  1. An email client like Gmail or Outlook uses SMTP to send an email to a sending email server.
  2. The email server uses SMTP as well to send the email to a receiving email server.
  3. The receiving email server sends the email to an email client through IMAP. The email is then downloaded and placed in the inbox of the recipient.

Why is it important?

SMTP is the protocol that governs the interactions between email servers around the world and ensures the deliverability of the 300 billion emails sent every day.

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