One of the items left out of vista is an SMTP server.  In XP and older operating systems you can have this installed with IIS.  However, vista does not include an smtp server.

You have a few options out there to download (http://softstack.com/freesmtp.html) or (http://www.smartertools.com/Products/SmarterMail/Free.aspx)

The most recent into is a project called papercut on codeplex.  This is my favorite for development. http://papercut.codeplex.com/ It receives messages but does not send them.  So you can just locally view your emails.

Steve (Steve Schofield) has a good post discussing this.  I wish I would have done a search before I started looking all over vista to find the app to install.

I am interested to hear the logic on why SMTP was not even an option or a downloadable option for Vista.  This may make it difficult for some developers to use their local machine

UPDATE (2010) – if you need a temporary fix for development try http://papercut.codeplex.com/