Jaroslaw Rafa:
> Dnia 17.10.2020 o godz. 18:25:13 Wietse Venema pisze:
> > For the port
> > 25 MTA-to-MTA service one can then reject all mail from a remote
> > site that claims to be from a local user.
>
> That's not a good idea. Assume domain.com is configured that way and some
> user on a completely different domain (us...@site.net) forwards their mail
> to us...@domain.com. Then what happens if some otheru...@domain.com sends
> mail to us...@site.net ?
[historical scenario omitted]
Exactly the scanario that SPF and the like are supposed to prevent.
Wietse
