How to use the mail() php function to send mail.
This works and is REALLY easy! And can be undone later. It's just editing a text file. I know it's scary and advanced (I was scared and confused at first), but just do it. It's fine. And if it doesn't work, you can change it back. Simple! :)
smtp.example.com is an example smtp server. It's different depending on your internet provider. I'm at Harvard now, so mine is: smtp.fas.harvard.edu.
I'm not really sure why this works, but here's what I think it's doing: postfix is a mailserver that comes installed on your Mac (like php does). MAMP uses postfix to send emails. By setting up a relayhost, it tells postfix to send the emails from your current ISP because before it didn't know how to send the email and the email just got stuck in a queue.
So, now all those old emails should be in your inbox, or wherever you sent them to! :)
If you'd like to view your mail log, it should be here:
FYI: I'm running Mac Leopard OS X 10.5.7 on one of the new MacBooks (with the silver titanium cover and black rim around the screen).
Thanks to Mike for this! I didn't trust him at first because it seemed too easy, yet sophisticated, but it works!