If you want to grant Send As permissions in Exchange 2010, you can use the Manage Send As Permission Wizard. In the Exchange Management Console, right-click the desired mailbox and then select Manage Send As Permission from the pop-up menu. In the Manage Send As Permission Wizard, click Add, and then use the Select Recipient dialog box to choose the user or users who should have this permission. To revoke this permission, select an existing user name in the Security Principal list box and then click Remove. Click Manage to set the desired Send As permissions.

An option to the Manage Send As Permission Wizard is the Exchange Management Shell. In the Exchange Management Shell, you can use the Add-ADPermission and Remove-ADPermission cmdlets to manage Send As permissions. The syntax of the Add-ADPermission cmdlet is as follows:

Add-ADPermission -Identity UserBeingGrantedPermission -User UserWhoseMailboxIsBeingConfigured -ExtendedRights ‘Send-As’

The following example of the Add-ADPermission cmdlet grants my user account Send As permissions to John Public’s mailbox:

Add-ADPermission -Identity ‘CN=Jim Doyle,OU=Engineering,DC=contoso,DC=com’ -User ‘CONTOSO\jpublic’ -ExtendedRights ‘Send-As’

The permissions granted above are removed using the Remove-ADPermission cmdlet.  The syntax of this cmdlet is listed below:

Remove-ADPermission -Identity UserBeingRevokedPermission -User UserWhoseMailboxIsBeingConfigured -ExtendedRights ‘Send-As’
-InheritanceType ‘All’ -ChildObjectTypes $null -InheritedObjectType $null -Properties $null

The following example of the Remove-ADPermission cmdlet revokes the permission assigned above with the Add-ADPermission cmdlet:

Remove-ADPermission -Identity ‘CN=Jim Doyle,OU=Engineering, DC=contoso,DC=com’ -User ‘CONTOSO\jpublic’ -ExtendedRights ‘Send-As’
-InheritanceType ‘All’ -ChildObjectTypes $null -InheritedObjectTypes $null -Properties $null