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Re: [ietf-smtp] IETF Policy on dogfood consumption or avoidance - SMTP version

2019-12-21 16:35:33
On Dec 21, 2019, at 3:47 PM, Keith Moore <moore(_at_)network-heretics(_dot_)com> wrote:
So if you don't have an explicitly configured hostname, do you simply refuse to 
send messages?   Or send EHLO  or what?
There's always a hostname.  It defaults to the return value of gethostname().
And if that contains no dots, and "mydomain" is not set, then the domain
defaults to "localdomain".  So worst case you get "shortname.localdomain".

But RFC 5321 says:

The domain name given in the EHLO command MUST be either a primary
      host name (a domain name that resolves to an address RR) or, if
      the host has no name, an address literal, as described in
      Section 4.1.3  <>  and 
discussed further in the EHLO discussion of
      Section 4.1.4  <>.

So, if it's a host name, it has to resolve. So, 'shortname.localdomain' 
wouldn't be valid.


Paul Smith Computer Services
Tel: 01484 855800
Vat No: GB 685 6987 53

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