Gmail normally sends as multipart/alternative, but it can be configured to send only text/plain. Unfortunately, when I try this Discourse sends me an email titled “Email issue – No Content” with the following body:
We’re sorry, but your email message to ["(email here)"] (titled Testing text/plain from Gmail) didn’t work.
We couldn’t find any content in the email. Make sure that you wrote something at the top of the email - we can’t parse inline replies.
If you’re getting this and you did include content, try again in UTF-8 plain text (no HTML).
I verified by Bcc’ing to another address that the message is sent with headers:
Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Is that just me, or is text/plain handling actually broken? This was sent as a new topic, if that matters.
(Top-post only is also a little disappointing, but that’s a separate topic and probably done to death.)