Anatomy & Timeline of an Email

Explore how an email travels from sender to recipient, visualizing each relay hop, authentication check, and delivery milestone. This page helps you understand the journey and security checks of a typical email.

Step-by-Step Breakdown

  1. ✉️ Sender
    Email composed and sent
    The user writes an email in their client (like Gmail, Outlook, or Thunderbird). When they hit send, the client formats the message, adds headers (From, To, Subject, Date), and connects to the sender's outgoing mail server.
    Timestamp: 2025-06-02 10:00:00
  2. 📤 SMTP Outbound
    Sender's mail server relays message
    The sender's mail server (SMTP) receives the message, checks sender authentication, and adds the first Received header. The message is then queued for delivery to the next server.
    Timestamp: 2025-06-02 10:00:02
    Time since previous step: +2s
  3. 🔗 Relay Hop 1
    First relay server
    The email passes through an intermediate SMTP relay. This server may perform spam or virus checks and adds its own Received header, recording the time and server details.
    Timestamp: 2025-06-02 10:00:04
    Time since previous step: +2s
  4. 🔗 Relay Hop 2
    Second relay server
    The message is relayed again, possibly across networks or organizations. Another Received header is added. Delays or re-routing can occur here.
    Timestamp: 2025-06-02 10:00:07
    Time since previous step: +3s
  5. 🛡️ SPF/DKIM/DMARC
    Authentication checks
    The recipient's server (or a relay) performs SPF, DKIM, and DMARC checks to verify the sender and message integrity. Results are recorded in the headers. If checks fail, the message may be rejected or flagged as spam.
    Timestamp: 2025-06-02 10:00:08
    Time since previous step: +1s
  6. 📥 Recipient Server
    Delivered to inbox
    The recipient's mail server accepts the message, stores it in the inbox, and makes it available for the recipient's email client to download or view.
    Timestamp: 2025-06-02 10:00:09
    Time since previous step: +1s