Exchange outgoing problems

I have server 2003 install with exchange 6.5 When i completed the installation a few months ago everything was running perfect. Then my outgoing mail just started stying in the queue. with this error “The remote server did not respond to a connection attempt”

First i check all my smtp settings, i use a smarthost for outbound mail. This was all fine as it was originally setup. I also tested my ISP’s smtp server through telnet which worked fine,

So i suspect the exchange is not sending it out for sum reason, no settings were changed. from the time it was working.

What is my next step?