[plug] Sendmail- masquerading

[Tim Bowden]

Hi all,
Fetchmail & sendmail have been set up (sort of) on the mailserver 
machine.  Fechmail is working fine.  Receiving mail is no problem. 
 Sending is.  No domain name has been setup on the mailserver machine- 
only the hostname.
The sendmail.cf has the following:

Djoffice
DMusername at isp.com.au
DSmail.myisp.com.au

Can DM be set this way or can it only be the the domain being 
masqueraded, ie isp.com.au?

When I send from an acount set up in mozilla as mylocalname at mailserver 
and try to send I get the error
"The mail server responded: 5.1.8<mylocalname at mailserver>...Domain of 
sender address mylocalname at mailserver does not exist"

What do I need to change.?

Given the masquerading setup, will all internal > internal mail appear 
to come from username at myisp.com.au?

Thanks,
Tim