ISP won't accept mail remotely from Exim but does with Mozilla

[Nate Bargmann <n0nb@networksplus.net>]

This is puzzling me a bit.  Ordinarily I use Mutt with Exim to send mail 
when dialed into my ISP.  However, tonight I am in a motel using their 
wireless and get rejected mail when I try to send a message from Mutt 
through Exim.  However, sending messages from Mozilla mail works fine.

I know that Mozilla talks to the ISP's SMTP server directly and the 
message ID is generated from the ISP's SMTP server.  However, Exim 
generates its own message ID and these messages are rejected.  How can I 
adjust Exim so it mimics Mozilla's behavior?

I am using Exim 3.36-13 on Testing.

Thanks!

- Nate >>