Originally Posted by manofice
if pin to pin worked the data plan is fine, are you sure you're using the SMTP email address for the user?
Delete user from the bes, do a security wipe to the device, readd the user, and try to enterprise activate it. Try it in that order. Also not sure what provider you're using but make sure the device reads the correct network
Had to do that on two of my users so far not bad odds, but a definite solution.
If that doesn't fix I would call the carrier and have them look at the two BlackBerries maybe they are tinkering with the plans on those 2 specific BlackBerries.