I will be moving from 8700 to 8800 by moving the SIM card from the 8700 to the new 8800, do I need to do something else in order to properly configure de BB internet mail system ?, thanks

Yep, whoever your carrier is, you will need to register the new PIN # on the site where you configure the BIS. There should be a place to CHANGE HANDHELD, where you enter the new PIN #, so the BIS will send the mail to the new device.

Like the above poster said. If you are on BIS you will need to go to your carrier's BIS site and enter your user name and password. Then hit change handheld and enter your new IMEI and PIN. Click on service books and send. You should be up and running!