Mail Forwarding to Gmail Broken?

Have you set up one of your email accounts to forward to Gmail, but test emails you send from Gmail don't get forwarded back?

I ran into this problem trying to set up forwarding from an external email account. None of the test emails I sent from Gmail showed up in my Gmail inbox. I thought it was a problem with the forwarding setup, and I went back and forth with the admin for the account, and even read through changelogs for the forwarding software to try to find mention of any relevant bug.

After many unsuccessful hours, I found the answer in a place I should've checked to begin with - the Gmail help pages. Apparently, emails you send from Gmail to a mailing list you're subscribed to, or an account that forwards to your Gmail, only show up in Sent Mail - not in your Inbox. Gmail says they do this to help prevent clutter.

So there you have it. The world isn't turning into chaos, and your mail forwarding is not broken after all, unless of course you're sending test emails from an account that isn't your Gmail account.