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 developed by RIM. 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.
Read more about this topic: Wireless Email