We unfortunately do not have a solution that will sync contacts, calendar and email between Microsoft Outlook and mobile devices.
We do however have a solution called 'mobile sync' that will sync contacts & calendar entries between webmail and mobile devices (but not desktop clients including outlook)
This is only available to our PremiumMail clients and cost for this can be requested from our support desk. It will involve an upgrade process for all users. Similar to gmail as the agents would need to use an online webmail interface. The 'mobile sync' option is optional for all your users, so the additional cost per mailbox would only apply to clients that want this.
The alternative is Gmail itself for business, but then you need to move all current email accounts over and there are monthly costs involved
If you'd like to explore this further please contact our support desk.