User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

Compose a message, for which the OpenPGP users(senders) public key will be attached (activation of key attachment has been implemented in bug1628097).

Actual results:

Stripped (minimal) senders public key is not injected in the header of the to be sent mail. (did not test this, but I did not find a bug that said this would be implemented, the suggestion of Patrick in bug1628097 to use Autocrypt header looks like it is not currently implemented)

Expected results:

Stripped (minimal) senders public key is injected according to Autocrypt specification in the header of the to be sent mail.

This was already implemented in Enigmail.
See Autocrypt implementation status: https://autocrypt.org/dev-status.html

For specification details see
https://autocrypt.org/level1.html#openpgp-based-key-data
https://autocrypt.org/level1.html#header-injection-in-outbound-mail

For the question of attachment of minimal or complete OpenPGP public key, see bug1629309

Just saw that there was a similar request regarding Autocrypt header in the TB-planning mailing list, which I was not aware of when filing this bug: https://mail.mozilla.org/pipermail/tb-planning/2020-June/007680.html

We can consider this at a later time, once we have the ability to strip keys.

Initial support was added in bug 1654767.