Thanks, Tomi, for your quick response. > > * If yes, for resent messages > > (https://tools.ietf.org/html/rfc2822#section-3.6.6), does notmuch use > > (the chronologically last) Resent-Message-ID, or the Message-ID? > > the Message-ID Hmm. Is this a conscious decision, or is the resending case just not taken into account? What happens if I have both a message and my own copy of it after resending it to somebody else? I would like to have a record of whom I resent it to, as with forwarded messages (where the forwarded message does have a different message id). Are the Resent-* headers of the resent message merged into the database entry? I guess this last question is more general: with multiple messages with the same Message-ID but differences (for whatever reason), how will these messages be merged in the database? Best, Erik