Apple Mail/gmail question?

I have a gmail account as my primary e-mail account. I receive and read my mail on Apple Mail. I just replied to a friend’s e-mail message to a hotmail account through Apple Mail, and in the lower left hand corner, Apple Mail showed three outgoing messages. That’s weird.

I tested the number of outgoing messages by sending a reply to another message from a different person, and it showed two outgoing messages. I sent a message to a second gmail account that I have, and it showed one outgoing message. What’s going on here?