Our business currently uses an external service provider -- with whom we have a close relationship -- to do Outlook/BlackBerry syncing. Their server is Exchange 2010 with BlackBerry Enterprise Server.

Everyone that is not provided with company BlackBerry's, are using POP or IMAP to access email.

That external service provider offers the service to several companies, all with a single domain (their domain) used within Exchange Server. Then each user has to go onto their email provider's webmail and forward their mail service to their username on the Exchange service providers server, such as: johnsmith@company.com > john.smith@contoso.com  Then the service provider just set's an alias with the correct email address for outgoing email, such as: johnsmith@company.com

We are extremely grateful for the level of control that BlackBerry Enterprise Server provides and wish to continue to have that managed by the external service provider; however, we also need the features available to us in Office365 including larger mailboxes, ProPlus Office suite, and SharePoint. And we would like everyone BlackBerry users and our current POP/IMAP users to all be on this cloud-based Office365 Exchange.

How can we do this so that the email/calendar/contacts/tasks for the BlackBerry users are synced between Office365-based Exchange that belongs to our organisation and the Windows Server- based Exchange that is owned by our external service provider?