You use Symantec Email Submission Client (SESC) on Exchange 2010 or 2013, which has a default subscription limit of 5,000 mailboxes. Or you have run into a different EWS throttling limit.
You want to remove the EWS limits for SESC.
1. On an Exchange Client Access Server (CAS) start the Exchange Management Shell from the Start menu.
2. Create a new throttling policy with no limits on EWS usage.
Run the following command in the Exchange Management Shell:
New-ThrottlingPolicy -Name sescThrottlingPolicy -EWSPercentTimeInAD $null -EWSPercentTimeInMailboxRPC $null -EWSMaxConcurrency $null -EWSMaxSubscriptions $null -EWSPercentTimeInCAS $null
This creates a new throttling policy with the name sescThrottlingPolicy.
3. Associate the new throttling policy with the SESC service account.
Exchange 2010 - no service packs
With Exchange 2010 and no service packs the only way to associate a new throttling policy with an account is through a mailbox for the account (see Throttling Policy Associations in Exchange 2010 SP1). Run the following command in the Exchange Management Shell:
set-mailbox <sescServiceAccount> -throttlingpolicy sescThrottlingPolicy
NOTE: Replace <sescServiceAccount> with the name of the SESC service account.
The following example associates the throttling policy with the account 2k8domain\svc01:
set-mailbox 2k8domain\svc01 -throttlingpolicy sescThrottlingPolicy
Exchange 2010 SP1 and higher
Run the following command in the Exchange Management Shell:
Set-ThrottlingPolicyAssociation -Identity <sescServiceAccount> -ThrottlingPolicy sescThrottlingPolicy
NOTE: Replace <sescServiceAccount> with the name of the SESC service account.
The following example associates the throttling policy with the account 2k8domain\svc01:
Set-ThrottlingPolicyAssociation -Identity 2k8domain\svc01 -ThrottlingPolicy sescThrottlingPolicy
Technical Information
More information about Microsoft Exchange throttling policies
Effects of Throttling on Your Deployment in Exchange 2010 SP1
Budget Snapshots in the IIS Logs
Understanding Client Throttling Policies
How to configure Client Throttling in exchange 2010