[imp] default identities

[Matt]

I have a machine running horde, imp, and MySQL, that sits on a company
intranet.  This machine does not need to trade email with any other
computers; it's just an easy way for many locations, not connected to
one another, to send messages back and fourth.  

 

Since it is only internal email, there is no dns for this machine.  It
is accessed by ip only.  When composing a message imp fills in the From:
field as username at .SYNTAX-ERROR

 

This of course causes and error when the recipient hits Reply.  I was
able to fix this by filling out an identity.  In the from field of the
identity there is now username at internal which is just fine.  When the
recipient hits reply the message makes it back to the original sender
just fine.  

 

The problem with using identities is that a user could easily put in
another persons username into the from field and the message appears to
be from the other person.  

 

What I need is a solution to either disable identities and still be able
to set them as the administrator (imp does not like it when you directly
change the prefs under SQL), or a way to only allow the user id that the
person has a password for, in the From: field.  

 

Any ideas?

 

Thanks for the assist.

 

Matt