On Tue, Jun 05, 2007 at 10:38:15PM +0100, Russell King wrote:
Search LKML for other mentions of Mail-Followup-To; this is far from the
first time it's been brought up.
I'm probably one of the few who actually investigated why their MUA was
suddenly doing weird, RFC-unfriendly things to the To/CC headers,
tracking it down the Mail-Followup-To header.