Mail you send or forward to a mailing list you subscribe to, or to an account that forwards messages to your Gmail account, will only appear in 'Sent Mail.' This is intended to help prevent clutter in your inbox. If a message isn't successfully delivered, you'll receive an error message in your inbox.
That's a bit disappointing. I'd rather have an option in the settings for that. I use the Gmail SMTP server, and never receive any of my own emails when I download with POP. It took me a while to figure out what was going on. I first suspected the Novell Forge email list setup since it swallows emails at random as well.