Proper config to handle idalup users?

[John Goggan <jg...@dcg.com>]

What is the proper way to configure SpamAssassin (and/or sendmail for that 
matter, possibly) to handle dial-up users that use our machine as their 
primary SMTP server?

Basically, I have some users that are on dialup (or, at least, dynamic) 
services out there now and then.  They connect directly to our machine for 
sending out email (either actually to us on the machine -- or relaying back 
out to the world).  To do this, I have added some of their IP ranges to the 
sendmail "access" file with permission to "RELAY".  I realize that this might 
allow a few unauthorized people to relay off of me -- but it should be a 
fairly small likelihood, so we've decided to live with that for now until we 
can get them moved to a static IP.

The problem is that all of their mail to us is being tagged with 
RCVD_IN_NJABL_DIALUP and RCVD_IN_DYNABLOCK.  Is there anything that I can do 
to prevent this?  Something to configure to tell them that I am their primary 
SMTP server and that therefore, as far as our server is concerned, it isn't a 
problem that they were on a dynamic and/or dialup IP?

Either that -- or is there a better way to solve this?  Unfortunately, due to 
circumstances outside my control, I cannot make them switch to only 
authenticated SMTP nor can I move them to static IPs at this time.

Any thoughts?  Thanks...

  - John...