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Re: Debian and FQDN lookup

On Tue, 7 Apr 2015 13:23:33 +0200
Vincent Lefevre <vincent@vinc17.net> wrote:

> On 2015-04-04 10:02:22 +0100, Joe wrote:
> > On Fri, 3 Apr 2015 20:39:26 -0500
> > David Wright <deblis@lionunicorn.co.uk> wrote:
> > > I think I/we ought to be using .local
> > > http://tools.ietf.org/html/rfc6762
> > > because this won't get onto the Internet.
> > 
> > Really? I've seen an Exchange Server refuse mail from a BT server
> for this connection, the "BT server" is actually the client.
> > because the latter identified itself with .local as tld in the HELO.
> I doubt this has anything to do with BT. MTA's will generally provide
> the FQDN as the HELO name (as described in the corresponding RFC), and
> if the FQDN has been chosen to end with .local then you'll get that in
> the HELO.

My point was that the default is only of use for a machine directly
exposed to the Net, with a hostname resolvable in public DNS. This one
clearly wasn't, and its admin should have overridden the default. And
should have *known* that it was something he/she needed to fix.

> Anyway the HELO should really be ignored in practice as it
> provides no useful information for the recipient.

Possibly so, but it is currently an integral part of the SMTP
transaction, and it is a common requirement of a receiving mail server
that the sender's HELO be resolvable in public DNS. It's one of the
common options offered by exim4, though not the default.


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