> From: brian @
imcon .
ilinx .
com
>
> from the quill of "J. T. Judge" <sy71703 @
public .
fmr .
com>
> >
> > If you are application level, how do you deal with the
> > problem that internal mailers, network client programs, etc
> > can resolve A and MX records for "out there" -- but these
> > same client programs can NOT connect to those addresses ?
> >
> Ah, yes. I had to deal with this one over the weekend. I was fortunate in
> my decision to dump sendmail for smail a long time ago. With smail, you
> can tell it only to do a hostname lookup if the domain is known (i.e. I can
> list which domains to do a hostname lookup of) and I specify only our
> internal domain as known. This way mail to the inside domain gets looked
> up and passed via SMTP but mail to all other domains is routed to the
> smarthost.
>
I contend that Sendmail 8.6.x is now able to do this too. I am not
slamming smail here, but, rather, offering the solution to those still
using sendmail.
There are several hooks for this, and they include:
1) The ability to define a mailertable
this is an external database of hosts or subnets and the place to send
their mail. This allows one to circumvent a wildcard mx for a distributed
domain, or, avoid mx mailers that are broken. (PSI comes to mind.)
I had a client where he was in California, on one internet provider,
and his parent domain was in DC. The parent had a wildcard mx for out
bound email. The problem was that this host was A) Undersized and B)
the smtp implementation wasn't smtp compliant! The mailertable allowed
me to re-route mail destined for west-coast systems properly, and
save about 24 hours on average delivery time.
2) The definition of a smart host
this is used to deliver non-local mail, unless there is a wildcard mx
mailer defined for your domain.
3) Fallback MX host, when all else fails, this is a nice feature to get
the queueing off the local host and onto something that can deal with
delivery problems....
Happy mailing!
Lee
--
_______ ______________
| | | | Leland K. Neely | ________ |
| | | | U.C.L.L.N.L | |` | |
| | | |_____ P.O. Box 808 L-613 | |________| |
| | \______/ Livermore CA 94551 |____________|
| \_______/ Email: lkn @
llnl .
gov ___|______|___
\________/ Voice: (510) 422-0140 |____________|
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