What protocol sends email to a mail server

Email is sent to a mail server using the Simple Mail Transfer Protocol (SMTP). SMTP is a protocol used for sending and receiving email messages between mail servers. Here's a high-level overview of the process:

  1. Client: A user composes an email using a mail client (e.g., Microsoft Outlook, Mozilla Thunderbird, or a web-based email client like Gmail).
  2. Mail Client: The mail client breaks the email into smaller chunks, adds headers and footers, and converts the email into a format that can be sent over the internet.
  3. SMTP Client: The mail client establishes a connection to an SMTP server using the SMTP protocol (typically on port 25).
  4. SMTP Server: The SMTP server receives the email from the mail client and checks the recipient's email address to determine where to send the email.
  5. Mail Server: The SMTP server forwards the email to the recipient's mail server (also known as a Mail Transfer Agent or MTA) using the SMTP protocol.
  6. Mail Server: The recipient's mail server receives the email and stores it in the recipient's mailbox.
  7. POP3/IMAP: The recipient can then use a mail client to retrieve the email from their mail server using the Post Office Protocol version 3 (POP3) or Internet Message Access Protocol (IMAP) protocol.

SMTP is a store-and-forward protocol, meaning that it relies on intermediate mail servers to forward the email to its final destination. This allows email to be sent between different networks and domains.

Here are some common SMTP commands used during the email sending process:

SMTP is a widely used protocol, and most email clients and servers support it. However, it's worth noting that some email providers may use alternative protocols, such as ESMTP (Extended SMTP) or Submission Protocol, for sending and receiving email.