The iPhone, for example, has one email client. The same client is used to access POP3, IMAP and Exchange email. BlackBerries also come with one email client, which can also handle POP3, IMAP and Exchange email.
In the case of the myTouch, there will be three. First, because the myTouch 3G runs Android 1.5, a Google Gmail account is required. All Android phones are tied to a user's basic Gmail / Google account. The Gmail client within Android, however, doesn't handle any other email. It only talks to Gmail.
In order to make customers happy, there is a POP3 and IMAP client that end users can take advantage of if they want to snag their Yahoo or AIM email, for example. It is buried in the menu system of Android, but it is there.
Where does this leave corporate users? In pretty good hands, actually. HTC has developed its own email application for Android that interfaces with Exchange -- but that's all it does. It supports push email from Exchange. That means corporate users can access their work email from the myTouch 3G if they so wish.
It's too bad that a single client isn't used to manage all those email relationships. myTouch users may suffer from a bit of email schizophrenia by the end of a work day if they rely heavily on Gmail and Exchange. Managing two inboxes on one device can be a bit of a pain.
An interesting solution from HTC.