This message can't be moderated because the approval system is too busy and can't accept messages now. Please try resending this message later, or contact the recipient directly.

Hello All,

We have in house Exchange 2013 running on Windows Server 2008 Standard R2. I have a group of all employee in the organization called employee@mydomian.com 

but from last couple of days I am getting this error while sending email to above mentioned group.

The delivery failure message says-

This message can't be moderated because the approval system is too busy and can't accept messages now. Please try resending this message later, or contact the recipient directly.

Please Help me to fix the same.

Thanks, Manoj