Postal Letter

What is the meaning of the different codes on USPS tracking system?

I wonder.. what these mean: the first 2 letters of the codes: for instance, I receive items from US, with EB in front - they come for a week or 10 days max. And now have 4 with CJ i front and witing for them over 3 weeks. All they are Prioriry International. Have some with CP in front. Can somebody explain that to me. Maybe there is a connection, and that is why these with CJ are so late... Thanks

Public Comments

1. EB is usually for Express and CJ is more for delivery conformation which can be for first class mail to. I'm guessing they end in US, right?