On Qui, 28 Nov 2013, Tom H wrote:
Since gmail threads messages by subject, if you reply to message and change its subject (with the new interface, I don't think this used to happen previously), the headers are reset.
But since the OP isn't changing the subject line (at least not in a visible way), I wonder what else he's doing wrong.
-- %TAG% Eduardo M KALINOWSKI eduardo@kalinowski.com.br