On 2017-01-03 13:47, Antony Stone wrote: > Given the increasing usage of Google-based business email services > (and others, similar), wouldn't that tend to prevent you being able to > manipulate the Message-ID header, because you are no longer in charge > of the outbound server used by senders on your domain?
Most MUAs insert a Message-ID header by themselves, and the MTA doesn't touch it. That is definitely how it works here, with mutt and exim. In fact my Message-IDs are generated by a script I wrote to override the mutt built-in ones. Even many gmail patrons use an IMAP capable MUA and use gmail as just a SMTP submission server. It doesn't work perfectly due to quirks in the gmail IMAP implementation, but it works. -- Please *no* private Cc: on mailing lists and newsgroups Personal signed mail: please _encrypt_ and sign Don't clear-text sign: http://cr.yp.to/smtp/8bitmime.html
