Re: domain names, was: hostname

[Dan Purgert <dan@djph.net>]

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).

> [...]
>
> 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.

> 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).


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