Redmine

Hi

Registration confirmation email triggers the following rspamd symbol:
Symbol: MV_CASE(0.50)

code for this check is:
rspamd_config.MV_CASE = { callback = function (task) return task:has_header('Mime-Version', true) end, description = 'Mime-Version .vs. MIME-Version', score = 0.5, group = 'headers' }

i.e. (at least AFAIU) it checks whether the exact (i.e. case-sensitive) header name given is 'Mime-Version'.

https://datatracker.ietf.org/doc/html/rfc1521#section-3 states

Messages composed in accordance with this document MUST include such a header field, with the following verbatim text:

   MIME-Version: 1.0

i.e. the case of 'MIME' needs to be all uppercase.