Weird JavaMail problem

[jamesl@xxxxxxxxxxx]

I've got the strangest problem with some Java code that uses JavaMail to
access 
an external (NT) mail server (without authentication). On our old
production 
system (V4R4), with a SOCKS proxy between it and the mail server,
the code 
works fine. But if I run the exact same CLASS file, with the exact
same 
"mail.jar" and "activation.jar," on our new production box (V4R5), it
gets a 
null pointer exception in the javax/mail/Transport.send0 method.
Looking at the 
source code for the Transport class (downloaded from Sun)
hasn't given me any 
ideas, except to tell me that "send0" is a private
method that is called from 
"send," and does all the "dirty work"
thereof.

--
J.Lampert