How Does Email Work Behind the Scenes

· Category: Tech Fundamentals

Short answer

Email travels through multiple servers using SMTP for sending, and IMAP or POP3 for receiving. It is a store-and-forward system.

Steps

  1. You compose an email in your client and click send.
  2. Your client connects to the outgoing SMTP server and transmits the message.
  3. The SMTP server looks up the recipient's mail server via DNS MX records.
  4. The message is forwarded to the recipient's server and stored.
  5. The recipient's client fetches the message via IMAP or POP3.

Tips

  • SMTP uses port 587 for submission with STARTTLS.
  • IMAP keeps messages on the server; POP3 downloads and often deletes them.
  • Spam filters analyze content and sender reputation before delivery.

Common issues

  • Misconfigured SPF, DKIM, or DMARC records cause legitimate emails to land in spam.
  • Large attachments may be rejected by size limits.