Re: Gnus with Exim

[David Abrahams <dave@boost-consulting.com>]

"Steven E. Harris" <seh@panix.com> writes:

> David Abrahams <dave@boost-consulting.com> writes:
>
>> I guess I'm confused.
>
> I think we fell out of step in our dialogue, so I'll just await any
> other specific questions you pose.

Okay, I'm going to ask you "what should I do next to configure Exim so
that I can send mail from anywhere?"

>> Sorry, I should be clear that I'm an ignoramus.
>
> That's what I know of you from Boost circles.
>
>> What's an MUA?  Mail User Agent?  A email client program?
>
> Yes, Mail User Agent. In this case, it's Gnus.
>
>> Yes, it's only smtp.rcn.com, AFAIK, that's unresponsive.  Except
>> that port 25 is blocked to anywhere but smtp.rcn.com
>
> Good summary.
>>> I thought we started out with you saying that this direct
>>> sending often caused your MUA to hang, 
>>
>> If by "direct sending" you mean sending directly to the recipients
>> smtp server, I'm not allowed by my ISP to do that unless the recipient
>> happens to have an rcn.com email address.  In other words, I can only
>> send to smtp.rcn.com on port 25.
>
> In this case, by "direct sending" I meant having Gnus talk directly
> with some remote SMTP server rather than only talking to your local
> exim MTA. I missed your characterization that smtp.rcn.com is the only
> SMTP server that you perceive to be slow. I thought you were annoyed
> by the lag waiting on any remote SMTP server.

OK, truth be told some others are a little slow.  And if I have
something big to send it doesn't really matter how slow the server is
because Gnus or my internet connection will limit things.  So OK, I
want to run Exim.

> [...]
>
>> Sounds like a reasonable approach to me, unless it soaks a lot of
>> cycles to try DNSLookup.  The queue should be empty most of the time,
>> so it's probably okay.
>
> I doubt it's cycles so much as just waiting through some tolerant
> timeout.
>
> Another drawback I've found with using the dnslookup/non-smarthost
> setup: Some ISPs such as AOL will not accept inbound messages if they
> can't do a reverse-DNS lookup on your IP address. When I try to send a
> message to a recipient at AOL, exim connects to AOL's SMTP server
> which in turn examines my IP address. Since my company does not expose
> names for all the internally-assigned IP addresses, the reverse-lookup
> fails and AOL rejects the inbound message. I therefore have AOL and a
> few others on an exclusion list that forgo the direct SMTP connection
> in favor of a smart host.

Yes, I've run into that.  What's worse, my sysadmin at
boost-consulting.com has inserted an intentional response delay to
foil spammers (he says it's incredibly effective) and other sysadmins
are lowering their reverse-lookup timeout to foil spammers.

> Here's a sketch of that router. It says that any mail not destined for
> a local user and to anyone at mycompany.com or aol.com should use the
> smart host mail.mycompany.com. This router precedes the dnslookup
> router we've been discussing.
>
> ,----
> | non_local_corporate:
> |   driver = manualroute
> |   domains = !+local_domains : *mycompany.com : *aol.com
> |   transport = remote_smtp
> |   route_list = * mail.mycompany.com
> `----
>
> I include this just to point out that it's hard to make a firm choice
> between smart host relaying and direct SMTP connections. Lots of
> policies out of your control govern what you'll find to be possible.

Well, I guess I've also occasionally run into places where I can't
reach my favorite smtp servers, but I'd be satisfied with a
configuration that tried smtp.rcn.com and then fell back to
smtp.boost-consulting.com.  That scheme seems to work in 99% of all
locations.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com