Use this script to grant "Send As" and/or "Receive As" permissions to a mailbox to allow the trustee to receive and send mail as that user.

download the script here or copy the example below:

The syntax for using this script is:

cscript SendAs.vbs domain\mailbox domain\trustee [Send As] [Receive As]

eg

cscript SendAs.vbs mydomain\fred mydomain\charlie True True

This will grant Charlie "Send As" and "Receive As" to Fred's mailbox

' ------------------------------------------------------------------------------------------------------------------------------------------

Option Explicit

Dim objArgs : Set objArgs = WScript.Arguments
Dim sTarget,sTrustee,bSetSendAs,bSetReceiveAs

bSetSendAs = True
bSetReceiveAs = True
if objArgs.Count < 2 Then : ShowSyntax
If (objArgs(0) = "?") Or (objArgs(0) = "-?") Or (objArgs(0) = "/?") Then : ShowSyntax
sTarget = objArgs(0)
sTrustee = objArgs(1)
If objArgs.Count > 2 Then
    If UCase(objArgs(2)) = "FALSE" Then
        bSetSendAs = False
    Elseif UCase(objArgs(2)) <> "TRUE" Then
        ShowSyntax
    End If
End if
If objArgs.Count > 3 Then
    If UCase(objArgs(3)) = "FALSE" Then
        bSetReceiveAs = False
    Elseif UCase(objArgs(3)) <> "TRUE" Then
        ShowSyntax
    End If
End If

SetSendAsReceiveAs sTarget, sTrustee, bSetSendAs, bSetReceiveAs

' ------------------------------------------------------------------------------------------------------------------------------------------

Sub ShowSyntax
     Dim sString
     sString = "Syntax:" & vbCRLF & " cscript " & WScript.ScriptName & " domain\target domain\trustee [Set Send-As] [Set Receive-As]" & _
                    vbCRLF & "eg:" & vbCRLF & " cscript " & WScript.ScriptName & " mydomain\fred mydomain\Charlie True True" & _
                    vbCRLF & " cscript " & WScript.ScriptName & " mydomain\Fred mydomain\Charlie False True" & _
                    vbCRLF & " cscript " & WScript.ScriptName & " mydomain\Fred mydomain\Charlie"
     WScript.Echo sString
     WScript.Quit(1)
End Sub

' --------------------------------------------------------------------------

Function SetSendAsReceiveAs(sTarget,sTrustee,bSetSendAs,bSetReceiveAs)
Const ADS_ACETYPE_ACCESS_ALLOWED_OBJECT = &H5
Const ADS_FLAG_OBJECT_TYPE_PRESENT = &H1
Const ADS_RIGHT_DS_CONTROL_ACCESS = &H100
Const RIGHT_DS_SEND_AS = "{ab721a54-1e2f-11d0-9819-00aa0040529b}"
Const RIGHT_DS_RECEIVE_AS = "{ab721a56-1e2f-11d0-9819-00aa0040529b}"
Dim objSdUtil, objSD, objDACL, objAce1, objAce2
SetSendAsReceiveAs = False
On Error Resume Next
Err.Clear
Set objSdUtil = GetObject("LDAP://" & WinNTToLDAP(sTarget))
If Err.Number <> 0 Then : Exit Function
Set objSD = objSdUtil.Get("ntSecurityDescriptor")
Set objDACL = objSD.DiscretionaryACL

Set objAce1 = CreateObject("AccessControlEntry")
objAce1.Trustee = sTrustee
objAce1.AceFlags = 0
objAce1.AceType = ADS_ACETYPE_ACCESS_ALLOWED_OBJECT
objAce1.Flags = ADS_FLAG_OBJECT_TYPE_PRESENT
objAce1.ObjectType = RIGHT_DS_SEND_AS
objAce1.AccessMask = ADS_RIGHT_DS_CONTROL_ACCESS

Set objAce2 = CreateObject("AccessControlEntry")
objAce2.Trustee = sTrustee
objAce2.AceFlags = 0
objAce2.AceType = ADS_ACETYPE_ACCESS_ALLOWED_OBJECT
objAce2.Flags = ADS_FLAG_OBJECT_TYPE_PRESENT
objAce2.ObjectType = RIGHT_DS_RECEIVE_AS
objAce2.AccessMask = ADS_RIGHT_DS_CONTROL_ACCESS

if bSetSendAs Then : objDACL.AddAce objAce1
if bSetReceiveAs Then : objDACL.AddAce objAce2

objSD.DiscretionaryAcl = objDACL
objSDUtil.Put "ntSecurityDescriptor", Array(objSD)
if bSetSendAs Or bSetReceiveAs Then : objSDUtil.SetInfo
If Err.Number <> 0 Then : Exit Function
SetSendAsReceiveAs = True
End Function

' --------------------------------------------------------------------------

Function WinNTToLDAP(sAccountName)
    Const ADS_NAME_INITTYPE_GC = 3
    Const ADS_NAME_TYPE_NT4 = 3
    Const ADS_NAME_TYPE_1779 = 1
    Dim objTrans, oObject
    Set objTrans = CreateObject("NameTranslate")
    objTrans.Init ADS_NAME_INITTYPE_GC, ""
    objTrans.Set ADS_NAME_TYPE_NT4, sAccountName
    WinNTToLDAP = objTrans.Get(ADS_NAME_TYPE_1779)
End Function

' --------------------------------------------------------------------------