> Nico Williams <nico@xxxxxxxxxxxxxxxx> wrote: > > > > I think what you're objecting to is the section 4.3 and related text > > that conflates "does not accept e-mail" with "does not send e-mail". > Section 4.3 describes what is already done by existing implementations of > this spec. > Exim in its default configuration validates the domain part of email > addresses and will reject mail if the sending domain does not exist or if > its MX records point to nonexistent hosts. Exim also recognizes null MX > records and suppresses the target A and AAAA lookups and treats the domain > as invalid. However the null MX logic is just an optimization: Exim's > validation logic would get the same result if it tried to do the A and > AAAA lookups and found that . does not have any addresses. > Postfix does the same if you use the reject_unknown_sender_domain option. FWIW, the equivalent option in the Oracle MTA is called mailfromdnsverify. > There are good reasons for rejecting mail from invalid domains, e.g. > because you would not be able to send a delivery failure report. Yep. I believe setting this option is fairly common. Ned