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

["Schwartz, Fernando G. | @SCA" <fgs@example.com>]

On 1/11/21 11:41 AM, Christian Horn wrote:
> What do you think, how would you react?
> Have you hit similar situations?

Hallo Chris, I often test against < echo@example.com > (use to check  
against " TU-Berlin " as well) and check the return headers. Your setup  
must pass all 4 checks, which include:

--->>>
Authentication-Results: univie.ac.at;
	iprev=pass ( ... ) smtp.remote-ip= ...;
	spf=pass smtp.mailfrom= < your domain >;
	dkim=pass header.d= < your domain > header.s=mail header.a=rsa-sha256;
	dmarc=pass header.from= < your domain >;
	arc=none
--->>>

Otherwise, it's crazy talk from Deutsch Telco.

Further, if you check at < https://mxtoolbox.com/diagnostic.aspx >,

220 fluxcoil.net ESMTP Postfix (Debian/GNU) is missing a " rDNS " to the  
IP. That's probably the main issue.

Hope it helps. Cheers! フェルナンド