You may wish to have the ability to grant the "send as" permissions in the ARS MMC, without allowing the user to have the ability to grant native permissions in the MMC console.
Currently you can grant permissions to write to the edsvaSendAsTrustees virtual attribute and this will allow users to grant the "send as" permission to user objects in the domain when using the Web Interface.
But you may wish to have this functionality in the MMC.
At this time this is not available. Users will need the permissions to edit native security before they can grant the "send as" permission to user objects using the MMC.
Enhancement request TF00156728 has been submitted.