Can't see true sender anywhere when using Firefox Relay

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App version

6.603

Where did you get the app from?

None

Android version

8.1.0

Device model

No response

Steps to reproduce

1. Receive an email from an alias address provided by Firefox Relay
   1.1. One can easily be set up for free at https://relay.firefox.com/
2. In the overall inbox/folder view (where multiple message previews are shown): notice that the original subject is displayed, but the sender is listed as the relay address, and the sub-header / preview text is "This email was sent to your alias...". On its face this behavior may make sense, as the "sender" is technically the relay email, but it is not useful or helpful. I will contrast it to Thunderbird for desktop which lists in the "correspondents" column the useful and helpful value of "sender@domain.com [via Relay] relay@mozmail.com".
3. In the detailed view (after clicking on the message): The original sender is not displayed anywhere at all - instead it just shows relay@mozmail.com. Again I'll contrast this to Thunderbird desktop where the "from" field clearly shows who sent the message to the relay.

Note that item 3 and the issue title is not strictly true, as you can click to view the headers when in the detailed message view and dig through all of those to find the original sender. However this is inconvenient, the sender is not easy to quickly see among numerous other technical headers, and finding the sender this way may never occur to an average non-technical user.

Expected behavior

Allow me to view the true sender in the same way Thunderbird desktop does:
original@sender.com [via Relay] relay@mozmail.com

Actual behavior

Described thoroughly in steps to reproduce.

Logs

No response

Reproduce this in Thunderbird for Android 6.603 using a Firefox Relay alias, then trace the inbox preview and detailed-message sender displays described in the steps. Compare the visible sender information with Thunderbird desktop; done means the original sender is clearly shown alongside the relay address in both views.