Even if you have not set up your new Business email with a mail client, you can access and manage it via OWA – the Outlook Web App In the OWA you can perform most actions you would with the local mail client. But it also offers you some interesting features.
In OWA you can manage your ActiveSync list. It is a list of all mobile devices syncing data with your e-mail account. Those could be Windows tablets, Apple iPad, mobile phones or iOS devices.
You can access it if you click on the gear wheel in the upper right corner and choose Options >> Phone.
Have in mind you can only have up to 10 connected devices. It is a good idea to delete devices you definitely do not recognize from the list.
If you have connection issues with any of your devices you could click on it to select it and click on the Delete button at the top to remove it. That will force the device to re-sync. That will not remove the account setup from the device. The user will not be forced to reenter the password. The reconnection happens in the background.