Устанавливаются они на ПК пользователя. Дальше ситуация очень простая - пришла Вам, скажем, почта на mail.yahoo.com.
Откуда клиент может знать о появлении этой самой новой почты, если mail.yahoo.com в ее бесплатном варианте ничего кроме web-интерфейса не поддерживает?
Правильно, по расписанию, раз в некоторое время, этот клиент, зная Ваш login и пароль считывает страницу с mail.yahoo.com и на основании полученной информации формирует SMS в который включает пару строчек из заголовка письма и отправляет его на Ваш телефон.
Независимо от того, работает ли у Вас в данный момент GPRS и есть ли он на Вашем телефоне вообще.
On Monday Microsoft vowed to give its Exchange 2003 customers wireless push email capabilities similar to RIM's Blackberry Connect middleware for free in a service pack later this year.
By licensing its Exchange push software to Nokia and Symbian, Microsoft has indicated that it is prepared to weaken its smartphone platform in order to shore up its Exchange revenue.
This is entirely consistent with previous fits of Redmond paranoia, in which Microsoft feared that Windows would become "a poorly debugged device driver layer", in Marc Andreessen's reckless words. In this case, the argument is that RIM could expand its email capabilities to perform Exchange-like functions, leaving Microsoft to sell a rather expensive directory server.
But less well-known names which sell primarily to carriers have long promised to undercut RIM's license fee, too. One of these, Seven, has today found a partner in Yahoo!, offering a carrier-based push email for a tenth of the price of RIM's Blackberry Connect. It isn't an Exchange service, and it is periodic delivery rather than true push; but it does the job.
Yahoo!'s mobile email is initially a modest deal, available only to Sprint PCS customers in the US, but it bring the capabilities to the consumer at a very low cost: $2.99 a month. It's available on five devices including the Treo 650 and 600.
