In my experience of web developer, I always had some trouble in testing serverside generated emails, especially for seeing what happens with the headers and general format of the message. Especially while working with Windows (you know, Internet Explorer is still widely used).

Now I’m developing a very little SMTP dummy server which will allow you to see what happens when your PHP’s mail() function (or other language equivalent) is called in your server-side scripts. I won’t say anything about the release date, ’cause I’m working on it during free time. Now it only works for my special purposes, I don’t feel it’s ready for public.

I can only say that Micro SMTP Server is being written in Java (so it is cross-platform) and it will be open-source (or almost free of charge).