Off topic: smtp HELO question

[Quartz]

>> I do use TLS, but what I'm trying to debug is not so much that the
>> email service *I* use checks, but that the final receiving server
>> scans through the headers and flags anything with a NAT address.
>
>
> It's probably not that. I suggest you try:
>
>   https://www.mail-tester.com/
>
> it may reveal what the problem is, unless it's just a BOFH on the
> receiving end doing something very odd.

I get a 7/10 (apparently because I never set a SPF to hook my mail 
service to my domain?).