Exch: repair the missing system mailbox

1、Exchange AD  Expand ：

1） Download and unzip the latest  Exchange Server  install  ISO  file .

2） Carry out orders ：

.\Setup.exe /IAcceptExchangeServerLicenseTerms /PrepareAD

   - Exchange Server 2016 CU22、Exchange Server 2019 CU11  Or more ：

.\Setup.exe /IAcceptExchangeServerLicenseTerms_DiagnosticDataON /PrepareAD

2、 Rebuild mailbox ：FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042

    The display name ：Microsoft Exchange Federation Mailbox

    Mailbox function ： This mailbox store is used to maintain different Exchange Joint data between organizations . This includes Rights Management Service、Cross-premises Mail-flow Monitor detection and response 、 notice 、Online Archive、Messaging Records Management and Cross-premises busy / Free information .

Enable-Mailbox -Identity "FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042" -Arbitration