Entourage

First, the timestamp on an email is almost meaningless unless you have specific knowledge of its accuracy.

Second, email is not necessarily instantaneous. Messages can be delayed for any of several reasons.

Third, you are using Entourage.

 

Electronic voodoo - I've experimented with sending emails from my office to my .mac address and my earthlink address at the same time - sometime the .mac comes in faster, sometimes earthlink does - it's a strange thing. My guess is that sometimes emails float around in servers backed up in a line of sorts until they can be delivered. Sometimes it's the senders ISP other times its the recipients. It's not an Entourage only thing - it happens with Apple's mail program as well.