When this issue occurs, if you run the Set-TransportConfig -SafetyNetHoldTime command to set the Safety Net hold time on the Edge Transport server, the operation fails. Additionally, you receive an error message that resembles the following:
Set-TransportConfig: You can't configure the 'SafetyNetHoldTime' property on a subscribed Edge Transport server.
Configure this property from inside your organization and allow EdgeSync to replicate the changes.
This is a code issue.
To work around this issue, add the "SafetyNetHoldTimeInterval" key under the EdgeTransport.exe.config file on the Edge Transport server, and then restart Microsoft Exchange Transport service.
For example, add the following line to the EdgeTransport.exe.config file:<add key="SafetyNetHoldTimeInterval" value="2.00:00:00" /> Notes
The minimum value for the SafetyNetHoldTime parameter is two days, and the maximum value is 10 days. If you set it lower than two days, the system will default back to seven days.
Even though the change is applied through the EdgeTransport.exe.config file, if you run the Get-TransportConfig cmdlet in Exchange Management Shell, it still reflects seven days as the SafetyNetHoldTime parameter.
To reduce the size of the mail.que file, make sure that you drain all the messages from the server, and then delete or re-create the Queue database. To do this, see the How to drain messages from the server section in this article.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
How to drain messages from the server
Pause the Microsoft Exchange Transport service to let the existing messages drain completely. No new messages will be accepted during this period.
Stop the Microsoft Exchange Transport service.
Delete all queue database files and transaction log files.
Start the Microsoft Exchange Transport service.
For more information, see How Safety Net works.