[Samba] NT domains

[Meli Marco]

I have two NT domains, MYDOMAIN1 and MYDOMAIN2 in the same network but
in two separated sites.
I have configured two SAMBA servers for each sites:
[global]
workgroup = MYDOMAIN1
security = domain
Domain logon = yes
password server = MYSERVER1,
it is the same for the MYDOMAIN2.
In this way when I access to my SAMBA server, with my 95/98/2000
clients, I can connect only on my local domain [MYDOMAIN1], but if I
want to connect and reach a share on the other SAMBA server, in the
other site?!?!
How can I do?
If one user want to connect to a linux-share on  MYDOMAIN2 from
MYDOMAIN1, I mean.I think that it is not possible, because the
autenticated of this user will make only on MYDOMAIN1, he does not exist
on MYDOMAIN2.
So in the same way, if I have the users that does not work with SAMBA,
but they are members' local domain, and use outlook client, they have
problems to connect on EXCHANGE/MYSERVER1, because this users does not
exist in the Linux SAMBA server.[Domain logon = yes]  
Can you help me,please.
Thank you
Marco. 
Risposta anche in italiano, grazie (il mio inglese non è dei migliori)