Set server into maintenance mode

Set-ServerComponentState SERVER1 -Component HubTransport -State Draining -Requester Maintenance

Restart-Service MSExchangeTransport

Restart-Service MSExchangeFrontEndTransport

Redirect-Message -Server SERVER1 -Target SERVER2

Suspend-ClusterNode SERVER1

Set-MailboxServer SERVER1 -DatabaseCopyActivationDisabledAndMoveNow $True 

Get-MailboxServer SERVER1 | Select DatabaseCopyAutoActivationPolicy

Set-MailboxServer SERVER1 -DatabaseCopyAutoActivationPolicy Blocked

Set-ServerComponentState SERVER1 -Component ServerWideOffline -State Inactive -Requester Maintenance

Take server out of maintenance mode

Set-ServerComponentState SERVER1 -Component ServerWideOffline -State Active -Requester Maintenance

Resume-ClusterNode SERVER1

Set-MailboxServer SERVER1 -DatabaseCopyActivationDisabledAndMoveNow $False

Set-MailboxServer SERVER1 -DatabaseCopyAutoActivationPolicy Unrestricted

Set-ServerComponentState SERVER1 -Component HubTransport -State Active -Requester Maintenance

Restart-Service MSExchangeTransport

Restart-Service MSExchangeFrontEndTransport

Get-ServerComponentState dkcphmail10a | select component, state

C:\Program Files\Microsoft\Exchange Server\V15\Scripts> .\RedistributeActiveDatabases.ps1 -BalanceDbsByActivationPreference -Confirm:$false