I would say it's possible, but I can see two things that you may not like to hear.
1 - Since it's a Blackberry, you are limilted to the Blackberry service. Even if you said that you are just going to use it to do emails, you may still need the Blackberry plan to connect to the RIM network to actually get your emails. If you can't, then you really can't. Blackberries are really different in hardware and plans compared to those like Treos.
2 - Assuming that you can connect to the network without a specific plan, you are going to be charged at whatever rate per kilobyte Verizon would charge.
To put it simply, you are going to need some kind of Blackberry plan, even the lowest/cheapest plan, in order to have your emails without hassle.
Hope that this helps, and good luck.