Marc Lucke via Postfix-users:
> On 15/09/2023 12:08 am, Wietse Venema via Postfix-users wrote:
>
> > Marc Lucke via Postfix-users:
> >> re:
> >> https://techcommunity.microsoft.com/t5/exchange-team-blog/updated-requirements-for-smtp-relay-through-exchange-online/ba-p/3851357
> > That text is about relaying email: you originate a message, and use
> > Postfix to ask a Microsoft email service to deliver that message
> > to some recipient on the Internet.
> >
> > As documented at the link that you cite, Microsoft requires that
> > the SMTP client is authorized to use the MAIL FROM domain.
> >
> >> Let's say I send an email. I use:
> >>
> >> > mail from: <annoy...@spammer.com>
> >>
> >> and in the data (body)
> >>
> >> > From: Professional Legit Person
> >> <igotalovelybunchofcoconuts@innocent.pizza>
> > That appears to be a different use case: you are not originating a
> > message for some recipient on the Internet, instead you appear to
> > be using Postfix to forward a message from the Internet to a Microsoft
> > email service.
> >
> > For this, your best bet is to forward the message as an attachment,
> > instead of inline. That is, create a new email message, from your
> > email address, and attach the forwarded message as message/rfc822.
> >
> > I do this sporadically, using the 'forward' feature of a mail reader
> > program. If you want to do this in some automated manner, perhaps
> > Bill Cole has some tooling suggestions.
> >
> > Wietse
>
>
> Thanks Wietse. Not my use case. It's a simple store & forward MTA &
> the senders will always be local & authorized - that's already taken
> care of.
You need to prove that to a remote SMTP server (e.g., Microsoft)
with DMARC, DKIM, SPF, and so on.
> I literally would like to know how to make it so that whatever
> the "mail from: " that was used is none of Microsoft's, or anyone
> else's, business, & if that's possible. But I'm also annoyed that I
> have to.
You would have to invent time traval and go back 20 years, when
email receivers were more liberal in what MAIL FROM address they
accepted.
Wietse
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