SendAs permissions granted to users in forests trusted by Microsoft Exchange Server are not visible in the Send As Permission Wizard in Exchange Management Console (EMC)


Symptoms


Send As permissions granted to users in forests trusted by the Microsoft Exchange Server forest are not visible in the Send As Permission Wizard in Exchange Management Console (EMC) 2010.

Cause


This is the current design in Exchange 2010.

Workaround


To view all accounts that have SendAs rights on a mailbox , you can use this powershell command instead : 

Get-ADPermission <mailboxname> | where {($_.extendedrights -like "*send-as*") -or ($_.accessrights -like "*Generical*")} |fl *


For further information, please see Manage Send As Permissions for a Mailbox