www server question

[Brian Densmore]

Gerald,

>... 
> Any number of things can trigger a DNS lookup.  Is anyone 
> else using your
> box as a DNS server?  Do you have a web, ftp, or any other 
> type of server
> on the box?
The box is a web/mail server. The DNS is used internally by the web and
mail server, because I have multiple domains running on the box (apache
virtual domains). So I suppose the mailer daemon may be doing the DNS
look-ups. Which leads to another question. I get one of the following
errors for each e-mail processed:

Sep 16 04:02:20 dunsmuir sendmail[25788]: gethostbyaddr(172.21.12.130)
failed: 1 

What is the cause of this? I believe I have the DNS set up as a
non-authoritative caching name server, with the local domains listed and
it then points to the ISP DNS. This box is sitting on a LAN outside my
ISP's firewall.

> ...
> Any "from" entry in your maillog should be accompanied by a subsequent
> "to" entry with a matching message ID (assuming the message 
> was accepted
> by the server).  The "to=," bugs me - if delivery was made using the
> "local" mailer, shouldn't a user/mailbox name be listed?

I now believe that these messages are being dropped by sendmail as
errors. I have sendmail set up to send the errors to the postmaster.
Could it be that sendmail is not logging the errors being sent to the
postmaster?

Also neither party responsible for this spam has responded to my e-mail
to them asking for an explanation. Any recommendations on how to deal
with these persons (one is in Canada and the others is in places unknown
- they are asturg at fundy.com[DNS clearflow.com], and
postmaster at networkpromotion.com)? 

Thanks for all the help,

Brian