A Throttling Policy allows administrators to limit the amount of resources each user can take to avoid possible performance issues. In regards with EAS, a policy can control 6 parameters:
The one we are interested is EASMaxDevices which together with EASMaxConcurrency are the only ones set by default.
If the limit of 10 is reached, a user will receive the following message on the device he/she is trying to synchronize (in this case I changed the limit to 1 for testing):
To overcome this limitation, you can increase this limit using the Set-ThrottlingPolicy cmdlet. For example, to change it to 25, run the following cmdlet:
Set-ThrottlingPolicy <policy_name> –EASMaxDevices 50
If you don’t want to increase everyone’s limit, you can create a new Throttling Policy, increase its limit and assign it to the user(s) you want:
New-ThrottlingPolicy "Increased EAS" -EASMaxDevices 25 Set-Mailbox Nuno -ThrottlingPolicy "Increased EAS"
Alternatively you can delete any devices that you no longer need to sync with Exchange, if any. To achieve this, login to Outlook Web App, go to Options -> Phone -> Mobile Phones and delete any unused partnerships to reduce the number of devices associated with your account.
For more information: Set-ThrottlingPolicy