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Re: domain names, was: hostname



On Thu 22 Mar 2018 at 22:17:02 (-0000), Dan Purgert wrote:
> David Wright wrote:
> > On Thu 22 Mar 2018 at 08:58:43 (-0400), Greg Wooledge wrote:
> >> [...]
> >> An SMTP receiver SHOULD validate the recipient address right here,
> >> right now.  It SHOULDN'T just accept everything and then figure out
> >> whether it's deliverable later -- that enables joe-job spam.
> >
> > How is it meant to do that. If it's relaying, the system it's
> > eventually going to send the message to might not even be
> > running just now. Email is store and forward, isn't it?
> 
> If it's *relaying*, it is not *receiving*; there's a subtle but key
> difference there.  At most, a relay will likely validate 
> 
>  
>  - source (host or user) is allowed to relay via me.
>  - destination is a FQDN
> 
> The closest that a relay will "store-and-forward" is in essence similar
> to if your roommate (significant other, etc.) is going out ... you say
> "hey, since you're gonna go past the mailbox, mind dropping these in
> there for me?".  That is, it will only "store" the message long enough
> to dump it off at the intended recipient (as defined by the MX Host for
> the target domain).

I took "receiver" to mean the sense used here:
"Message transfer can occur in a single connection between two MTAs, or
in a series of hops through intermediary systems. A receiving SMTP
server may be the ultimate destination, an intermediate "relay" (that
is, it stores and forwards the message) or a "gateway" (that is, it
may forward the message using some protocol other than SMTP). Each hop
is a formal handoff of responsibility for the message, whereby the
receiving server must either deliver the message or properly report
the failure to do so."
https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol

Some of us remember when emails passed through several gateways and
could take a couple of days to reach their destination. We used to
spend our time juggling addresses containing multiple ::, @, and %
delimiters, with hops through JANET (which at that time wrote its
addresses backwards), EARN, BITNET and Inmarsat, all kicked off by
pasting the message into a Telex on BT Gold. Academic institutions
could only afford to link up through Inmarsat a couple of times a
day at most. I could only afford BT Gold (out of hours) because a
friend managed an experimental comms project at university. This
was how it was in the mid-late 1980s.

> > [...]
> >
> > My last point may become less true over time because, as I already
> > just posted, there is now an authoritative answer: If you don't
> > know what to put, put home, corp, or mail, as you wish. They are
> > guaranteed never to become TLDs in the future.
> 
> They're as guaranteed to "not" become as TLD as much as ".local" or
> ".me" or ".tech" were guaranteed to "not" be a TLD in the 1990s.

Perhaps this was pre-ICANN? Do you have a reference? Or a contact inside
ICANN that knows something nobody else knows about resolution 2018.02.04.12.

> > I'm not convinced that I, and many in my situation, would be better
> > off running a mail server rather than having an organisation run a
> > smarthost to do it on my behalf. (They also take care of incoming mail
> > by running an IMAP server.)
> 
> Ultimately it depends on how far you trust your ISP.  Cox is pretty good
> (at least they were when I was in their service area).  TWC/Spectrum was
> generally good, but they could break hard.  AT&T (Yahoo) is completely
> useless.
> 
> Also, by running your own mailserver, you are not bound to your ISPs (or
> google's, etc.) size limits / ads / etc.  For example, my parents can
> send me 50MB emails (old and refuse to learn dropbox / owncloud for pics
> of their grandkids ... so they send mails, and I put them where they
> belong).

Yes, it's tedious that Cox sends a marketing letter every week expounding
their TV service. Oh, you didn't mean that? Which ads do you mean?

Cheers,
David.


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