Problems with sending email over SMTP in .NET?

I occasionally have problems sending email to my own local SMTP server, and get pretty paranoid that your recipient might actually get a test email that they're not actually supposed to get.

You know you haven't set SMTP up properly on a .NET website when you get an error like this: "Failure sending mail" or "No connection could be made because the target machine actively refused it 127.0.0.1:25"

My advice? Don't bother setting SMTP up on your local box. What's the point when you can intercept all outgoing email and view what you're going to send (and to whom) with a little application that sits in your system tray!

Enter SMTP4Dev. I'm going to sound like a JML advert, or possibly sound like I work for them (I don't), but I can't recommend this little application enough. It requires no config whatsoever provided that you're going to use port 25 for SMTP, and it's free!

That URL again: SMTP4Dev.