-------- Original Message -------- On 2 Aug 2020, 17:02, Bill Cole < [email protected]> wrote:
> if you want to authenticate email, ... The helo is a necessary, but not sufficient criteria for authentication. I use them all, up to dane. However, they all fail with those two senders, because they do not implement them, and they send mail from an IP whose rDNS is that of the ISP. Authenticating the source in this case reduces to cheching the sending IP against those from known valid e-mails, as well all rfc compliance as evidence of some degree of home work from their side. I am talking about a bank and an accountancy firm, and I resent having to do this.
