Is it possible to synchronize mail on three different devices on shared hosting (classic platform)? Specifically...
When I read an email, I want to show as 'read' on the other two devices.
When I send an email, I want it to appear in the 'sent items' folder on the other two devices.
The three devices are a laptop, netbook, and a BlackBerry.
Currently each email account is set up as a POP3, with the option to leave mail on the server.
POP3 by nature does not have this capability. If you configure your account as IMAP4 instead, you can achieve this, since it's more like a "window" into the email that's saved on the server. Similarly, an Exchange-based email account will also support this, and if you configure your account on your devices as ActiveSync, it can support push syncing as well.
Using POP3 nothing syncs at all, choosing to leave mail on the server simply makes it possible to access that mail on the server later but it can only be accessed one way (your computer or device reading from the service).
So while you could get your inbox on all devices, your outbox or sent items will not ever appear on the server using pop3. You would need at least an IMAP to achieve this.
I believe the classic platform email (xmail) will support IMAP however so you can possible simply adjust your Outlook or email software settings to use that instead of pop3.