Subject: [Emailcore] Ticket #9: G.7.3. Resolvable FQDN in SMTP and private domain names

From: Alexey Melnikov <[email-masked]>
Date: Mon, 16 Nov 2020 17:20:06 +0000

Dear WG participants,

Another rfc5321bis issue for your consideration:

In Section 2.3.5 ("Domain Names"):
     Only resolvable, fully-qualified domain names (FQDNs) are permitted 
when domain names are used in SMTP.

John's Note (as the editor): does "in the public DNS" or equivalent need 
to be added to "resolvable"???

My personal opinion: I don't think we should require "in the public 
DNS", as as SMTP works just fine with split horizon or private DNS servers.

In order to stimulate discussion of this topic I would like to propose 
the following strawman:

"Resolvable" can mislead readers to think that they need to attempt 
resolve all domain names when received. I don't think this is intended. 
I would like to propose to drop "resolvable" from the sentence quoted 
above. Possibly discuss "private domain names" in the Applicability 
Statement draft.

Thoughts?

Best Regards,

Alexey

---

From: Ned Freed <[email-masked]>
Date: Mon, 16 Nov 2020 23:24:34 -0800 (PST)

> DNS", as as SMTP works just fine with split horizon or private DNS servers.

Agreed. While it can be convenient to perform DNS validity checks of the
domains in addresses in some contexts - or even more limited stuff like
checking for valid TLDs - it should not be an SMTP requirement. Requirements
like these lead to implementations imposing restrictions that are difficult
to remove - and there are cases where you want to remove them.

> above. Possibly discuss "private domain names" in the Applicability

Works for me.

				Ned