Funambol provides two methods for push email notification, SMS and TCP/IP, that enable mobile carriers to provide push email notification for customers. If you are not a carrier, you have a few options: 1) You can use TCP/IP push which is the best option to minimize battery consumption and bandwidth usage but some carriers might block it; 2) you can use SMS push. This might cost a lot, unless you receive few emails per day or you have an unlimited SMS message plan. This approach should work with most carriers but some might block it; 3) You can do scheduled pull (e.g. every few minutes). This approach might consume more or less battery, depending on how often you receive email. For example, if you get one email/minute and you pull every 15 minutes, pulling consumes 1/15th of the battery life vs. pushing.
This depends on several factors, including the push notification method used, the network and the device. In some cases, push notifications still arrive and in others they do not. For example, with SMS push, the SMS notification often gets to the device when it reconnects to the GSM/GPRS network.
