[Mimedefang] $helo versus $ip

[Lee Dilkie]

> No.  It's safe to reject an outsider who claims to be your domain (if
> you know for *sure* that it isn't), or who claims to have your IP
> address, but anything else can yield false positives.
>
> Regards,
>
> David.

And I think that's about as far as you can safely go without rejecting valid
mail.

I haven't, yet as far as I know, come across a valid mta that uses my ip
address or my hostname in helo. But I don't do any lookups on the address
supplied (if it was an address) because there are all sorts of valid cases
where you cannot tell if some mta is trying to scam you.

-lee