Explanation how sent mail shows "new" sent mail.

[GhostMac24]

Just trying to understand how sometimes I get "new" sent mail. Doesn't happen all the time but enough that it happens a few times a day to but a nuisance. For example, I will send something and then right after I will get a "new mail" indicator (shaded circle with the number) next to my "Sent" icon. Then I have to go into my sent mail, click on the message, and the "new mail" indicator will go away.

This is with my .mac account using the Mail program.

Thanks in advance!

 

[GhostMac24]

So I have been through all the settings and can't figure out what would be causing it. There isn't any feature box to check that would create this situation. I just sent an email and of course, right after it sent, I got a "1 new sent mail" icon. Here is a screen shot.