Need help bad with dns and smtp mail

[Colin Reinhardt]

I hope this isn't the wrong place to post this, but I feel I must now seek
the DNS gurus and SMTP administrators and this is where I presume you'll be.
Please excuse me if my post is inappropriate, here goes...

I have been struggling with a DNS and named SMTP mail configuration now for
several weeks.
My platform is Linux Slackware 2.2.6 and BIND 8.x (I believe).
I have been through DNS & BIND (cricket liu...) and the DNS HOWTOs to no
avail.

This issue is related to MX records and mail delivery. ( which is why I
cc'ed comp.mail.sendmail... )
I'm getting the error "451 - <colinrei at edgewaterhotel.com> ...
edgewaterhotel.com: Name server timeout"
named is up and running, and seems to be resolving correctly per my NSLOOKUP
tests.

What is odd is, inbound mail is delivered successfully from several remote
SMTP servers (including Hotmail, @home, etc...), but on others it will fail
with the above error NDR.  Outbound mail works fine.

I can't figure out what the difference is between those that can deliver
successfully, and those that fail with the above nameserver timeout.  As I
mentioned, I can trace the resolution of my DNS resource records correctly
down from the root servers, and I believe my MX mail exchanger info is also
correct.

Please, please.... if you have DNS experience and think you can help me,
please respond!
I will be glad to provide any additional information needed upon request.

Thank you,

Colin Reinhardt
Network Admin
Hotel Edgewater, Noble House Resorts