A common issue using the company e-mail server for development is SPAM which, sooner or later, will reach the customer or a third party. To avoid the problem I did use a very good dummy e-mail server the Dumbster. In May, last year, I had to send HTML formatted mails from my application and test the result on the most common E-Mail clients.
The Dumbster wasn't enough anymore, but I didn't want to install/configure a true e-mail server and maintain it. My new choice is Apache James because it is quite simple to setup and use. It supports MSOutlook and Thunderbird (and many other which I didn't really check).
