Send on Behalf and Send As are similar in fashion. Send on Behalf will allow a user to send as another user while showing the recipient that it was sent from a specific user on behalf of another user. What this means, is that the recipient is cognitive of who actually initiated the sending message, regardless of who it was sent on behalf of. This may not be what you are looking to accomplish. In many cases, you may want to send as another person and you do not want the recipient to be cognitive about who initiated the message. Of course, a possible downside to this, is that if the recipient replies, it may go to a user who did not initiate the sent message and might be confused depending on the circumstances.
Send As can be useful in a scenario where you are sending as a mail-enabled distribution group. If someone replies, it will go to that distribution group which ultimately gets sent to every user who is a part of that distribution group. This article will explains how to use both methods.
Send on Behalf=set-mailbox
http://technet.microsoft.com/en-us/library/bb123981.aspx
set-mailbox user2 – grantsendonbehalfto user 1Send As = Add-ADPermission
Give Send As Permission to user Domain\User to mailbox “mailbox alias”
Add-ADPermission “mailbox alias” -User “Domain\User” -Extendedrights “Send As”
you can read this article. http://technet.microsoft.com/en-us/library/aa996343(EXCHG.80).aspx
To use the Exchange Management Shell to grant full access permissions for a particular mailbox, run the following command to add the permission directly to the mailbox:
Add-MailboxPermission “Mailbox” –AccessRights FullAccess –User “Trusted User”
Get-MailboxPermission “mailboxalias” | where {$_.IsInherited -eq $false}To use the Exchange Management Shell to grant receive as permissions for a mailbox run the following command to add the permission to the mailbox ：
Add-ADPermission “commandes vmi” -User “dff\papa” -Extendedrights “Send As”
Add-ADPermission –Identity “Mailbox ” –User “Trusted User” –ExtendedRights Receive-AsThis example returns the permissions that have been applied to the user Ed.
Get-ADPermission -Identity EdThis example returns the permissions that have been granted to the user Chris on the Contoso.com Receive connector.
Get-ADPermission "Contoso.com" -User ChrisWhat is the difference between ADPermission and MailboxPermission?
Difference between AD permission and Mailbox permission is where the permission is stored (and, indirectly, on what object you’re setting the permission). AD permission cmdlet sets permissions on AD objects. Mailbox permission cmdlet sets permissions on “store mailbox” objects inside the information store. There’s a bit of overlap, however, because some of the permissions are AD permissions until the StoreMailbox object is provisioned in the information store, at which point they become read-only in the AD and are managed from the store object at that point forward.
As for extended vs regular rights in AD – the easy way to think of this is that generally the extended rights are the special things that are unique to an object (and are added for that object as part of its schema). So things that are particular to mailbox objects are going to be extended rights, while the common AD permissions for the mailbox object will be regular rights.