$User= Read-Host -Prompt "Enter Username"
$Mailbox=Read-Host -Prompt "Enter Mailbox"
Add-MailboxPermission -Identity $Mailbox -user $User -AccessRights FullAccess -WhatIf
Add-ADPermission $Mailbox -ExtendedRights Send-As -user $User -whatif
Add-ADPermission $Mailbox -User $User -Extendedrights "Send As" -whatif
-------------------------------------------------------------------------------------------------------------------------------
I get this error:
[PS] C:\Windows\system32>$User= Read-Host -Prompt "Enter Username"
Enter Username: User1
[PS] C:\Windows\system32>
[PS] C:\Windows\system32>$Mailbox=Read-Host -Prompt "Enter Mailbox"
Enter Mailbox: mailbox1
[PS] C:\Windows\system32>Add-MailboxPermission -Identity $Mailbox -user $User -AccessRights FullAccess -WhatIf
What if: Adding Mailbox Permission on 'mailbox1' for User 'User1' with AccessRights ''FullAccess''.
[PS] C:\Windows\system32>Add-ADPermission $Mailbox -ExtendedRights Send-As -user $User -whatif
mailbox1 wasn't found. Please make sure you've typed it correctly.
+ CategoryInfo : NotSpecified: (:) [Add-ADPermission], ManagementObjectNotFoundException
+ FullyQualifiedErrorId : [Server=TestServerExchange,RequestId=8aaf17a3-d6c1-47e7-ae05-5160614af63a,TimeStamp=10.11.201
6 15:37:50] [FailureCategory=Cmdlet-ManagementObjectNotFoundException] 533A71B,Microsoft.Exchange.Management.Recip
ientTasks.AddADPermission
+ PSComputerName : TestServerExchange.local