Ken Peng via mailop <[email protected]> writes:

> May 9, 2023 at 4:07 AM, "Gellner, Oliver via mailop" <[email protected]> 
> wrote:
>
>
>> 
>> If a receiver only accepts emails from sender addressed domains for which MX
>> or A records exist (such checks are performed by many receiving servers), it
>> means a sender has to 1. set up a DNS zone and 2. create a MX or A record
>> within it.
>
>
> No. A DNS zone is not needed at all for sending email.
>
> My ex-employer is a Nasdaq listed company, whose business email is with 
> @staff.sina.com.cn. It has MX only, not a zone.
>
> $ dig staff.sina.com.cn soa +short
>
> $ dig staff.sina.com.cn mx +short
> 10 staffmx.sina.com.cn.
> 10 staffmx1.sina.com.cn.

I agree with these pattern, because nowdays people like easy setup via
Cloudflare, with no serious.

> Also, my policy in Postfix has setted up to reject messages from 
> unknow_sender_domain, which means if a domain has neither MX nor A, it would 
> be rejected by me. 
>
> smtpd_sender_restrictions = permit_mynetworks, permit_sasl_authenticated, 
> reject_unknown_client_hostname, reject_unknown_sender_domain
>
>
> As you see, Postfix's reject_unknown_sender_domain validates only MX and A, 
> not SOA.
>
> regards.

Good comments, thanks!


Sincerely, Byung-Hee

-- 
^고맙습니다 _布德天下_ 감사합니다_^))//
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