FSRM: Failed to send the email alert.

Error

Windows Event Log:

A File Server Resource Manager Service email action could not be run.

Error-specific details:
Error: IFsrmEmailExternal::SendMail, 0x8004531c, Mailbox unavailable. The server response was: 5.7.1 Client does not have permissions to send as this sender

We will need to provide send permissions to the computer running FSRM

Add-ADPermission -Identity "MailboxName" -User "DOMAIN\Computeraccount$" -ExtendedRights "Send-as”