We have tests that ensure Discourse can receive mail for read-only categories that mirror a mailing list:
To support that, posts sent to mailing list mirrors bypass some checks:
def create_post(options = {})
…
if sent_to_mailinglist_mirror?
options[:skip_validations] = true
options[:skip_guardian] = true
else
options[:email_spam] = is_spam?
options[:first_post_checks] = true if is_spam?
options[:email_auth_res_action] = auth_res_action
end
def sent_to_mailinglist_mirror?
@sent_to_mailinglist_mirror ||=
begin
destinations.each do |destination|
return true if destination.is_a?(Category) && destination.mailinglist_mirror?
end
false
end
end
at a guess, something to do with your setup might create condition such that the fact it’s a mailing list mirror isn’t detected? Note that to bypass these checks, the mail has to be sent to the category email address and not the site’s reply_by_email_address.