Fix Discord adapter dumping raw HTML into DM preview for HTML emails

Some senders' text/plain fallback part contains raw HTML markup instead of
real plain text, which was getting truncated straight into the DM message
body. When an email has an HTML part, show a short notice instead of trying
to preview mail.text — the full message is already attached as message.html.

Psalm 25 17committed 2 months agoparent d72cb57a3ec38155dcda6bb38992972b80c1e7f804d638fBrowse files