I am trying to check whether an email that I sent has read-receipt enabled. According to this Q&A, I can search for Disposition-Notification-To in the headers. I've been able to view the headers for some messages using the following procedure:
- Click the 3 dots at the upper right corner of the message
- In the resulting popup menu, click
View - In the resulting popup submenu, click
View message details
For some messages sent by me, this shows the headers in a popup window. For others, the popup window is blank. It doesn't seem to depend on whether the message has an attachment.
Based on limited experimentation, it seems that messages that I CC to myself contain message headers. Messages that I don't CC myself do not.
Why doesn't this show the headers for all messages?
Do I need to CC myself on all messages to see the headers?