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Re: using exim directly instead of smarthost



On Wed, Nov 05, 2003 at 03:34:26PM +0100, Benedict Verheyen wrote:
> > On Wed, Nov 05, 2003 at 02:17:58AM +0100, Benedict Verheyen said
> >> Hi,
> >>
> >> i have configured exim 4 and it runs fine. I use the smarthost option
> >> and thus send mails via my ISP. I was wondering if i could do the same
> >> by NOT using the smarthost option and use my exim4 to do this?
> >
> > Yup, it's easy. Just reconfigure exim4 ("dpkg-reconfigure exim4-config"
> > or so) and tell it to be a "Internet host" (or whatever it is) instead
> > of "Internet host with smarthost".
> >
> > However, be aware that some remote mail servers block mail from dynamic
> > and domestic ip addresses, and will refuse all mail coming from you.
> > Hotmail and Yahoo at least do this.
> 
> I have my own domain but i use the nameservers of the ISP where i
> registered the domain name. Then they forward this to the address
> i have with my cable ISP. 

So... as long as your domain registrar's nameservers are being kept
properly up-to-date with your (dynamic) IP address, you're all set for
receiving mail directly.

If they're forwarding mail to your _e-mail_ address at your ISP, that's
a totally unrelated issue.

> Anyway, i could use that domain name as the
> domain name from where my mail originates so that hotmail and yahoo
> accept mail from here.

Wrong.  These places (plus AOL I believe) will *not* accept mail from
you. They don't care about what your domain name or return address says.
When your server connects to theirs to deliver a message, they check
your IP against a big list. If it's on the list of known-to-be-dynamic
IP's, they just hang up on you. Because only spammers send mail from
their own server on a dynamic IP, I guess.

> But the problem would be if people want to reply to a mail sent
> from my domain: no mx records exist that point to my own machine.

This is not a problem.  As long as your machine is on-line and the
nameservers are pointing to you properly, incoming mail will be fine
with no mx records.
You only need mx records if you have a second (or more) machine set up
to accept mail on your behalf when your server is down.

If you don't have a secondary (and hence no MX records) then when you're
offline the sending server will retry for however long it's configured
for (I believe the RFC's say something about three days for this)

> Anyway, it seems to me that if one wants to seriously set up his
> own mailserver, that it's best to get a static ip.

Perhaps.  Although you can address the dynIP blacklist thing by having a
conditional rule to use your ISP's smarthost for a list of domains, and
keep that list up-to-date with those bastards who use the blacklist.

And for incoming mail, no mx records or anything, just don't turn the
machine off for stretches >= 3 days at a time.  ;-)

> I might be able to do mailforwarding via the ISP so that they
> intercept the *@mydomain.be mails and forward this to me.

I don't think that would be relevant or necessary.

> But since i don't have a fixed ip, i would have to use the method
> you describe of having an intermittant service like dyndns or ddts.
> Then provider could forward mail to that domain name and these in turn
> to the ip i have at that time but with the danger of the periods of
> downtime when changing ip.

Well, I use dynDNS, and my "downtime when changing ip" is five minutes,
because that's how often I have ddclient check to see if my IP has
changed (and inform dynDNS if it has).

> Hmmm, i think i'll skip this setup until i ever own my own ip :)

That, of course, is entirely up to you.

	Cheers!
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