change email with provider change?

I have an unlocked 8700r with Rogers with a blackberry email, gmail and shaw cable email sent to the bb.
I will be down in the US later this year for a month and plan on using T-Mobile with a flexpay account and blackberry plan.
Would I access the T-Mobile Blackberry site and setup a new blackberry email and reset the gmail etc to go to the T-Mobile blackberry address or would the rogers blackberry email still "find" the blackberry now on T-Mobile?

Hope this makes sense.

Not really sure... Interesting question. Interested in knowing what happens.