with the built-in ActiveSync client (developed by Dataviz). Most other Sony Ericsson phones support IMAP IDLE push email quite well (only the inbox however). Other mobile solutions Most non-proprietary solutions are network independent, meaning that as long as a device is data-enabled and has an email client, it will have the ability to send/receive emails in any country and via any telephone company that has data service on its network. It also means that as long as the device is not SIM locked (in the case of GSM systems), the constraints of BlackBerry, such as network locking, vendor locking (BlackBerry devices and BlackBerry Connect devices) and data-roaming charges (for non-home access) are not an issue. For a GSM system, install a SIM card appropriate for the location, have the correct APN settings and one's mail will be delivered at local rates. Simulation using traditional email Traditional mobile mail clients may poll for new mail at frequent intervals, with or without downloading the mail to the client, thus providing a similar user experience as push email. IMAP allows many notifications to be sent at any time, but not message data. The IDLE command is often used to signal the ability of a client to process notifications sent outside of a running command, which effectively provides a user experience identical to push. Protocols In contrast to traditional email, most of the protocols used in popular current systems are proprietary. For example, BlackBerry uses its own private protocols. Both the Push-IMAP standard and parts of the SyncML standards are attempting to develop more open solutions. IETF Lemonade is a set of extensions to IMAP and SMTP to make them more suited to the demands of mobile email. Among the extensions are rapid IMAP resynchronization and a new NOTIFY command in IMAP. See also History of email References Email Wireless email