I picked up a blog post about this tip from one of my RSS feeds. Amr ElGarhy posted a valuable article on how to write emails to a local directory rather than sending them through a mail server. This saves a lot of time in dev.
Essentially, replace your existing mail configuration with the config below:
<specifiedPickupDirectory pickupDirectoryLocation=”c:\tmp” />
When you send a mail using the built in .NET classes, a *.eml file will be created in the directory you specify. You can then view the email by simply opening the file.