[CLUE-Tech] Sendmail on a local network

[Jim Ockers]

Keith,

> Questions:
> Q1: Why doesn't sendmail like an IP address in the destination and prefer a
> hostname instead?

Sendmail is quite tightly integrated with the DNS.  It uses many functions of
DNS for proper reliable mail delivery, which is why a DNS name is best for the
address.

This is just speculation, but consider an e-mail address @yahoo.com.  The top
level domain is .com and is in the root zone.  Consider another e-mail address
@123.234.254.254 .  The top level domain is .254 .  Do you think that is in the
root zone as a domain?

Remember that there is no technical reason why you couldn't have a number as
a top level or second (or other) level domain, in the DNS.  Right now it's
not permitted by NIC policy but AFAIK it would work with BIND.

> Q2: Why would Mozilla mail (on the Linux machine) work to send to the MS SMTP
> on the Windows machine but the "mail" command line fail?

Once again mail is probably trying to resolve a name or address or something
in the DNS.

If you were to set up internal DNS with full forward resolution for all your
internal systems (inverse DNS is not necessary for sendmail to deliver mail),
and get all of the systems to agree on who is the DNS master for the zones,
**AND the DNS is set up properly with MX records**, you would find that your
e-mail would work quite reliably.

Hope this helps,
Jim

-- 
Jim Ockers, P.Eng. (ockers at ockers.net)
Contact info: please see http://www.ockers.net/