1. A wireless communications system comprising: a plurality of wireless communications networks; a plurality of mobile wireless communications devices for sending and receiving wireless electronic mail (email) messages over said wireless communications networks; and a resource deployment server for storing a plurality of resource deployment packages (RDPs), each RDP comprising deployment content and deployment instructions therefor relating to sending and receiving email messages; said resource deployment server also for dynamically deploying RDPs to said wireless communications networks to update deployment content thereof based upon the respective deployment instructions.