[SGVLUG] email: Can I send it out directly?

John E. Kreznar jek at ininx.com
Mon Jun 12 20:07:03 PDT 2006


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David Lawyer <dave at lafn.org> writes:

> But what about my outgoing email?  When I dialup to my ISP use the
> internet, I'm connected to the internet.  Exim (or sendmail, etc.)
> could just send out my outgoing email to the Internet, bypassing the
> mail server at LAFN.  I haven't set it up this way, but if I did,
> will it work?

It ought to.  There's a different set of problems.  For one thing, if
the addressee is not on line and has no MX, the mail will remain in
the queue on your machine.  Exim will normally make further attempts
until it either finds a place to send it or a timeout (typically
around a week) occurs.  You would want to run exim from ip-up or
something, to take advantage of each connected period.

> Will [addressee servers] accept mail from an IP number that is
> roving (assigned to my isp)?

You're asking the right questions.  I think the answer depends on the
specific addressee and may change with time as administrators try
whatever they can think of to filter out spam.

> What if my email is not accepted and returned to my temporary ip#
> just as I hang up my ppp connection.  Then who gets the return
> packets?  Not me since I'm offline.

If it's sent it's now the responsibility of whatever host accepted it.
If it's not sent, there's nothing to return, because the original is
still intact on your machine.  This positive hand-off is a feature of
SMTP.  The hang-up routine that you use should avoid interrupting SMTP
connections if possible.

If a bounce occurs later, you will see it returned to you as incoming
mail.

> And then what about authentication?

Good question.  Even with a domain and a static IP, rejection of mail
from dial-up hosts has been trending upwards.  It's a bit of a jungle,
as people try to find ways to keep legitimate mail moving while
stopping most spam.  Sometimes you have to negotiate with the
addressee administrator, or have your correspondent do so, to open a
particular channel.

> Don't spend any effort checking out my questions since I'm just
> curious and don't really have any need to send email directly.

By the same token, don't accept my response as gospel.  I haven't been
without domain and a static IP for fourteen years (mostly dial-up) so
I'm definitely rusty about the alternatives.

- -- 
 John E. Kreznar jek at ininx.com 9F1148454619A5F08550 705961A47CC541AFEF13
  Imagine there's no countries / to kill or die for  --John Lennon, 1971

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