What is SMTP (Simple Mail Transfer Protocol)?

SMTP gets your message across.

Think of SMTP as a one way post office for your emails. It can send them but it can’t receive them. SMTP or simple mail transfer protocol is a TCP IP protocol for sending messages, but cannot queue messages at the receiving end.

So, SMTP is usually used in conjunction with protocols that receive and manage messages like post office protocol or pop three or internet message access protocol or IMAP. SMTP works as a three step process.

  • First, an email server uses SMTP to send a message from an email client, like Gmail or Outlook, to an email server.
  • Second, the email server uses SMTP as a relay service to send the email to the receiving email server.
  • Third, the receiving server uses, let’s say Gmail for this example, to download incoming mail via a receiving protocol, like IMAP.

And that’s how a message ends up in your email inbox. SMTP remains the most widely used email protocol four decades after its inception. However, there’s been some trend towards using cloud -based HTTP or hypertext transfer protocol APIs to send and receive email.

HTTP APIs offer two main advantages. The communication between email client and server, for example, when using mobile apps, is faster than SMTP because HTTP APIs require fewer back and forth commands to authenticate the sender and recipient. And APIs offer functionality that is not available using SMTP, like process automation and extra security.

Sam Adai
Sam Adai
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