[weesteev]

The Blackberry uses the BES (Blackberry Enterprise Server) to push data to your phone. The blackberry will not "search" for email as the network sends it directly as soon as an email has been picked up by your POP or IMAP email server. Thsi has no bearing on your data limit as its not part of the broadcast data network (your 3G basically).

You shouldnt incur charges for any data access for email usage unless its being run through a third party app like Gmail which wont use the BES. You would need to be receiving a HELL of a lot of emails to breach your daily AUP limit on BB email, by default all graphics are turned off and attachments tend to be filtered beyond 10Mb so that help. In many years of (heavy) Blackberry email usage on many networks, I have yet to see a single charge for email usage.

Also, your twittier app will count towards your data usage as it transmits over the GSM network.

Hope this helps