[Rspamd-Users] blocking HTML_MIME_ONLY

[Thomas Groman]

How can I reject mail incoming to my opensmtpd server that doesn't have
plaintext content and is HTML only? I don't even have an html capable
mail client so i'm not going to be able to read it anyways and most
html-only mail comes from spamming agencies like mailchimp and
whatever. People who harvest my email address and send me repeating
mail I didn't ask for.

I'd like to be able to reject the mail at the connection level with
something like "550 envelope rejected see https://useplaintext.email/".
Instead I've only managed to figure out how to jack up the spam
weighting score for that identifier and send those to junk. But I don't
want those sent to junk I want them refused.