User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:93.0) Gecko/20100101 Firefox/93.0

Steps to reproduce:

Used file\save as or Ctr-S to save message as htm document on local Windows 10 device.

Actual results:

Saved document no longer begins with message header information, as it did in previous version before 91. Document consists of message body without header. Header information with sender, recipients, subject and date is needed.

Expected results:

Expected message header at the beginning of the document, as in previous versions of Thunderbird.

My testing shows using Ctrl+ S to save as works as follows;
saves the header in formation for the EML format.
For the document formats, text and HTML, it does not.

Alice, can you catch the regression range?

Regression window:
https://hg.mozilla.org/comm-central/pushloghtml?fromchange=1d81d0c7d689925122e9febf5bf048bd0edfa4a8&tochange=9b4135fcf96dee01ffe7ee6b6229ff6dc8d69669
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=bf16dfb1a2297df01a2b9143f2f1fa6bfa29da66&tochange=1bbf4362b266645db009c5895b8dd5a41ebb09a9

Pushed by geoff@darktrojan.net:
https://hg.mozilla.org/comm-central/rev/d2404125017d
Add Email headers in saved emails as .html files. r=mkmelin

Sorry, I backed this out because it busted a lot of tests. Removing the early return fixed the tests, but it wasn't clear to me if returning should then happen in the next block down like it used to.

Here's the back-out.
https://hg.mozilla.org/comm-central/rev/f3a42608496213cb061780ef202b68e9ca469beb

I'm not sure if it's related, but on trunk with an artifact build the message header is never showed.
From digging around a bit it seems that the nsMimeHtmlDisplayEmitter::BroadcastHeaders() is not triggered when a message is selected.

Confirmed.
With the patch backed out the message header is visible again on macOS.
This doesn't seem to affect Windows and Linux for some reason.

Thanks I'll look into it!

TB 91.3.1 not fixed on Windows version. Still no header included when message is saved with htm extension. Header was included through TB 78.14.0.

Of course. It's not fixed even on daily yet.

Try full: https://treeherder.mozilla.org/jobs?repo=try-comm-central&revision=97b231d69f9bfa900cb00434690b72887c4bf62e
Try with fixed xpcshell-tests: https://treeherder.mozilla.org/jobs?repo=try-comm-central&revision=eaba00f255744ad752dd60cfbfe7563e24f36736&selectedTaskRun=IRKTwhWWTiyvJjtDsEzyxA.0

Depends on D132035

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/cc05890fd454
Add test coverage for saved emails through nsMessenger::saveAs for .eml .html and .txt. r=darktrojan
https://hg.mozilla.org/comm-central/rev/42bbd1c757c2
Add Email headers in saved emails as .html files (like they used to). r=mkmelin

Comment on attachment 9252316 [details]
Bug 1738031 - Regression: Add Email headers in saved emails as .html files. r=mkmelin

[Approval Request Comment]
Regression caused by (bug #): comment #3
User impact if declined: Using "Save As" on emails doesn't include the header information on the saved file.
Testing completed (on c-c, etc.):
Risk to taking this patch (and alternatives if risky):

(In reply to Nicolai Kasper from comment #16)

User impact if declined: Using "Save As" on emails doesn't include the header information on the saved file.

The header information are not shown on if saved as .html.

Comment on attachment 9252316 [details]
Bug 1738031 - Regression: Add Email headers in saved emails as .html files. r=mkmelin

[Triage Comment]
Approved for esr91

Thunderbird 91.4.1:
https://hg.mozilla.org/releases/comm-esr91/rev/1bb89bdf1798
https://hg.mozilla.org/releases/comm-esr91/rev/b4724f1de4a9