exchange2k3: mail stuck at SMTP connector   

Dear all,

i am having problem sending email out from the domain. after tracing the 
email, the email apperently stucked at the server connect.
We do not use default SMTP virtual server, we uses routing group  to smart 
host.

we using exchange 2003, 2 server clustered. from the queue, it shows that it 
is stuck at the smtp connector.

with the similar mail, we zip up the files and send. using this mathod, the 
mail went throught.. same destination as well...

is there any possible way because the email contain, 2 msg file, 1 of the 
msg file got a zip file

could it be anything to do with it? .

date: Mon, 28 Jan 2008 12:16:08 +0800   author:   Leezy