Is your BB connected to a BES server? No mail is stored on the server to my knowledge. But if this is a personal device and you are connected to a BES server be aware they can wipe your device if necessary. Also any policies applied to the device will stay on the device even if the account is deactivated on the server, unless they remember to deactivate the policies before deactivating the account. If the company owns the device you will need to wipe it yourself before turning it in or others will be able to see what is on it. But email received to the BB from a personal account does not get added to or stored on the server, no.