On 26.11.2017 18:46, Ian Zimmerman wrote: > those are Exim's local IDs, assigned by the list server host. Those > are distinct from RFc 5322 Message-IDs, which are the closest thing > to uniquely identify a message.
I am well aware of this, and this is exactly what I wanted to point out. > So from the above it cannot be concluded that Peter's system sent the > message twice: it might have, but it might equally have been the fault > of the list server. Peter's email was either sent to both of the following smarthost03a.mail.zen.net.uk [212.23.1.20] smarthost03d.mail.zen.net.uk [212.23.1.23] in short succession or magically duplicated. Just save both messages and run 'diff' to verify this. The other MUA-generated headers appear to be identical, including "Message-ID: <1722168.phgiPb26BP@peak>". While it is possible that zen.net.uk screwed up, I consider it more likely that the message was sent twice, as more of their customers would notice a systemic problem and probably be quite vocal about it. There's nothing to be done if the smarthosts are actually stupid hosts anyway. ;-) > FWIW, I am _not_ seeing any duplicates on this list [...] Does NeoMutt perhaps suppress dupes based on message ID? Thunderbird obviously does not. -Ralph
