On Fri, 2012-01-20 at 16:31 +0100, Reindl Harald wrote:
be careful with rewrite mailbody this will break all sorts of signed mails
Though that problem exists, anyway, even if you do nothing. Because mail comes to you through more than one server, any of which may transform an email in transit.
A /smart/ system might leave signed messages alone. Though I have my doubts if anybody's thought to do that. Some servers are notorious for mangling message content, particularly list servers that will add their own footers to them.