I am using Tomcat for a JSP project. Usually I leave the server on (running on windows 2000)until it get involved with my email system. I send out email from outlook, and people complain that they didn't get the content of the email for several times, and someone complains that they didn't get my email at all. It happened about 4-5 times then I have to turn Tomcat off.
Are you using javamail to interface with an exchange server? Where does outlook come into play? I have seen wierd things where exhange did wierd things when accessing it directly as an SMTP server as opposed to using CDO or another activex-type thing to send email through it.