An email consists of headers and the actual content of the message (body). The header allows you to trace the sending process of the email. It forms the letterhead, from which you can determine the following information:
- The sender
The servers that were involved in the transmission from sender to recipient
However, most email programs do not display the headers at all or only in excerpts while in the standard configuration. In this article, we'll show you how to view the headers in different email programs and webmail services.
Was your email not delivered, but instead you received an email with an error message and status code (bounce message)? If so, you may find it helpful to view one or both of the following detailed articles:
- Can't Receive Emails (For emails coming to your IONOS email addresses)
- Sending Emails is Not Possible (For emails that you, as a IONOS customer, are sending to others)
Why would I need information from the email header?
- Isolating email sending and receiving problems
- Gathering detailed information that IONOS Customer Service can use for troubleshooting your issue
- Authenticity verification through the IONOS Email Validation Service
Viewing Headers in Email Programs
- Thunderbird (and other Mozilla clients)
Open the email, click the More button on the right, and then select the Show Source action from the menu.
- Outlook 365 (via Internet browser)
In the email details view, click the 3-dot menu to the right of the heading. Select View > View message details.
- Outlook 2010/2013/2016
Double-click to open the email and click File > Properties from the menu. Now navigate to the Internet Headers section.
- Windows Mail
Right-click on the relevant message and select Properties. Now click on the Details tab where all the header info is displayed.
- Apple Mail (on Mac)
Open the email and press Shift + cmd + H (⇧ + ⌘ + H) keys on the keyboard simultaneously.
Open the corresponding e-mail and right-click on the message text. Select View All Headers and Message from the context menu.
Viewing Headers in Webmail Services
Open the email and click the drop-down menu on the right (down arrow, next to the date and reply button). Select Show original in the next selection. This will open another window with all the header lines (under the "Download original message" button).
Open the email and click on the icon with the three horizontal lines on the right. Select the option Show source data in the following menu.
- GMX Mail
Open the email and click on the info icon (i) on the right. A window opens with the header information.
- Yahoo! Mail
Open the email, click More and then View Raw Message. The full headers will now be displayed in a new window.
- AOL Webmail
With the email open, click on the Details button in the upper area. Then the header lines will be displayed in a new window.
- Outlook Web App (new version)
Open email and click the down arrow button (v, to the right of Reply) in the upper right corner. In the context menu please select the option Show message source.
- Outlook Web App (old version)
Open email and click on the icon with the three dots [...] in the upper right corner. In the context menu, please select the option Show message details.