Gmail w/Apple, sent mail into INBOX????

It's the way Gmail organizes email. It saves your replies, and makes your "conversation" with the recipient a "thread", like those you see on this forum and all others. This makes it easy to follow conversations, and keeps the mailbox neat.

While it works great in Gmail's web client, it messes with the external client because the external client doesn't organize email the way Gmail does, and so sees all messages as separate emails. You'll just have to live with it.

 

Mail.app does, however, have an 'Organize by Thread' item in the View menu, which may help to partially alleviate the problem.

 

Yeah, it's gmail's fault, but you can tell Mail to ignore it or even move/delete it. Set a rule:

If any of the following conditions are met:
From Is Equal To your gmail address
Perform the following actions:
Mark as Read

Of course, if you're prone to sending email reminders to yourself, this would interfere with that...