Testing SMTP without sending an actual email itself

My colleague was asking me about sending an email using SMTP. He was wondering if we could send an email without actually sending an email and it will just land on a disk for inspection. I don't remember any tool that will do that so I did a research.

I found about SMTP for Dev (http://smtp4dev.codeplex.com/)

What it does are the following :

1. Sits in the system tray and does not deliver the received messages.
2. The received messages can be quickly viewed, saved and the source/structure inspected. 

It is actually useful for debugging before you actually have your application send an actual email.