With the current pre-parse event (mail filtering), we"ve already evaluated and processed the message to a certain extent. This means that structural problems with the message (where it"s not following spec, for instance) can"t be addressed.

When gmail ignores the faulty MIME headers and displays a message that we can"t (because it"s technically broken), it"d be nice to be able to have that event point where it"s still a raw email and we can "fix" it.

The specific use case I"m referring to is a mailer (belonging to an important client of a customer, so they can"t make them fix it) that improperly claims a message is "multipart/mixed" when it"s just a plain-text message. Changing the MIME header allows the message to parse, but we can"t do that in the mail filtering because it"s already been processed by that point.