Thank you for the explanation.
Is it really risky to implement "always_add_missing_headers" if other headers (i.e. From) are present? https://www.postfix.org/postconf.5.html#always_add_missing_headers Thanks! ------- Original Message ------- On Friday, November 11th, 2022 at 13:17, Markus Schönhaber <[email protected]> wrote: > 11.11.22, 13:02 +0100, Juan Smitt Jr: > > > Can you help me please understand the "message-id" header? > > > > Sometimes it's missing from the emails and i.e. gmail rejects these emails. > > > > Is it added by the email client (application) or is it added by postfix? > > > The Message-ID header contains an unique identifier for the particular > message[1]. Every message should have one, and in general, especially > when real people communicate via e-mail, it's the sending MUA's (mail > client's) job to create one. > Depending on situation (for example when postfix itself creates a status > message) and configuration postfix might create a Message-ID, though. > > > [1]: https://datatracker.ietf.org/doc/html/rfc5322#section-3.6.4 > > > -- > Regards > mks
