How to View Full Email Source and Header in Fastmail

View Full Header and Source in Fastmail

Want to access an email’s raw source for troubleshooting, tracing or security? Find out here how to view the full email source and header for any message in Fastmail.

First, You Need More Than a Window to Know Window-Weather

Bright skies and sunshine and a few clouds in between: the glance through the window from within is a clear call to go outside.

If, outside with a t-shirt and shorts or a light pullover perhaps, we find ourselves freezing and shivering and looking longingly inside through that window, we have experienced “window-weather”.

In Iceland (and in Icelandic), window-weather is gluggaveður: weather that appears more appealing through a window than it is when you experience it outside. To identify window-weather from inside, you need a window, of course, and at least a weather report (or a thermometer maybe outside that window).

Now, can I lure you into looking through that window onto bright email code and a few header lines sprinkled in?

How to View the Full Email Source and Header in Fastmail

Time needed: 2 minutes

To access the full message source (including all header lines) for an email in Fastmail on the web:

  1. Open the message whose header lines and source code you want to access.

  2. Select Actions in the message’s header area.

    Fastmail keyboard shortcut: You can press ; (colon) to bring up the Actions menu.
    Mobile: The same steps work in the desktop and the mobile version of Fastmail on the web.

  3. Choose Show raw message in the menu that appears.

    Using the keyboard: You can use the down keys (and up keys) to navigate the menu, then select Show raw message with Enter.
    Access all email headers and the full source code for an email in Fastmail

  4. Find the full message source in a new browser tab or window.

    The header: The header lines start at the very top and end with the first completely empty line; the email’s message body follows.

How to View the Full Email Source and Header in Fastmail: FAQ

Can I access the message source without opening the email first?


The Actions menu and its command to open the raw email source are only available once an email is open.

Can I open the message source and headers in the Fastmail app?


The Fastmail apps for Android and iOS let you open the message source using the very steps above. The source code opens in a new browser tab in your default browser outside the Fastmail app.

(How to view the full email source and header in Fastmail tested with a desktop browser; first published October 2023, last updated May 2024)

Home » Email Tips and Resources » How to View Full Email Source and Header in Fastmail