Comment 2 for bug 1539390

I was not suggesting not doing policy/security filtering of posts. If such filtering changes a message, that message obviously cannot be handled in "Keep Headers" mode and needs to fall back to one of the other methods.

I was suggesting simply not doing the purely cosmetic message munging where that munging would invalidate an enforced DKIM signature (or a PGP signature if a poster uses that). In other words, no suffix prefixing, no reordering of "Re: " prefixes, no msg_header and no msg_footer. For many messages this would be enough to leave the message intact so it passes signature validation.