A few years ago I discovered MockSMTP. MockSMTP is a Mac application that establishes a local SMTP server. What is great about MockSMTP is it captures all email and displays the messages in a list similar to Apple Mail. This is useful for things like testing html emails, contact forms, and account registration. Anything that interacts with email can be tested faster.
To connect your web service to MockSMTP all you need to do is configure your SMTP settings to point to your localhost at port 1025. MockSMTP will handle the rest.
MockSMTP is worth the price. It is $9.99. If you’re interested you can download a trial from the developer’s website.