[tlug] [slightly OT] SMTP and the internet, protocols and the internet

[Christian Horn <chorn@example.com>]

Hoi tlug,

please allow me to be a bit offtopic, but not to much.
Like some other people on this list, I run services on the
internet: a web-, a mail server and more.
I have domain fluxcoil.net from the .net servers delegated
to me, so I host the domain myself, can create subdomains 
and so on.

Some weeks ago I sent new years greetings to some friends,
3 also with mail addresses @t-online.de .  My postfix was
not able to deliver, these mails were refused with:

[..] 554 IP=45.136.30.123 - A problem occurred. (Ask your 
postmaster for help or to contact tosa@example.com to 
clarify.) (BL)

So I contacted tosa@example.com, and was pointed at
https://postmaster.t-online.de/index.en.html .  I was
asked to comply with these rules to get mails from my
domain accepted, and was first hinted at chapter 4.1:

| In particular, we recommend choosing a host name that
| indicates its usage as a mail server (eg. mail.example.com) 
| and >>> to ensure the host's domain leads to a website 
| providing full contact details. <<<

Regarding that: I deliver mails from fluxcoil.net 
directly, and do not intent to change that.  _If_ I was
to change that, for example to mail.fluxcoil.net, what
then if google decides that only mails from 
foobar.<domain> are acceptable?  Such rules should be
decided with the internet community, and find their
way into RFC, to be acceptable.

2 mails back and forth, it was pointed out that I
could also provide my full name and address on my
webserver.  I have actually name and multiple ways
to reach me there - but I would not want to provide
my address there.  My full address was since ~2005
visible in whois for my domain, but recent changes
of the whois organizations have changed things.

So this is where I am.
I think these are rules artificially setup by the
mail provider, to make spam fighting easier for them,
but rising bars for accepting mails from domains like
mine.  Everybody on the internet is free to choose 
whom to accept mails from, or I could decide not to
have my webserver talk to some IPs.  I think there is
no higher instance watching there, the only way to 
fix this would be to illustrate the issue to enough
people, and maybe the provider rethinking this 
arbitrary rules.

I talked with some peers who know much more about
these things, but without a good way forward.

What do you think, how would you react?
Have you hit similar situations?

Chris

PS: slightly OT, as it's more about how to be a
good citizen on the internet.  But it's also about
how to run MTA services on the internet with Linux,
that is on topic.