Trigger Outlook Event: Change Signature

Does anyone know if it possible to trigger a signature change event in Outlook 2016? I.e. Simulate clicking a signature as per the screenshot below:

I am trying to change the signature automatically based on which 'From' address has been selected. I can capture the 'From' address change (as answered here).

However I cannot find a way to programmatically change the signature. My research has gotten as far as concluding that the CommandBar object is deprecated in Office 2016 and that I need to interact with the IRibbonUI object. Or perhaps some other Ribbon object? Or perhaps there is better way of selecting the signature other than faking a button click?

I cannot find a Signature object in the Outlook namespace with leads me to conclude that the MailItem class does not know about signatures - it only knows about body text. However what is odd is that I can right-click on the signature body and bring up a context menu:

So some object somewhere must know about signatures - perhaps the email editor?

Many thanks

Solution

Wow OK so figured this out but it is quite a roundabout way of achieving the result. Thanks to @niton for this handy comment to point me in the right direction.

In summary it performs the following:

Raise event when SentOnBehalfOfName property in MailItem is changed
Delete the current signature based on the presence of bookmark named _MailAutoSig
Select the html signature based upon which sender was selected
Insert the html signature file contents and add bookmark named _MailAutoSig

Here is the code I have implemented so far:

Dim WithEvents myInspector As Outlook.Inspectors
Dim WithEvents myMailItem As Outlook.MailItem

Private Sub Application_Startup()

    Set myInspector = Application.Inspectors

End Sub

Private Sub myInspector_NewInspector(ByVal Inspector As Outlook.Inspector)

    If TypeOf Inspector.CurrentItem Is MailItem Then
        Set myMailItem = Inspector.CurrentItem
    End If

End Sub

Private Sub myMailItem_PropertyChange(ByVal Name As String)
On Error GoTo ErrorCatcher

    Dim signatureName As String
    Dim signatureFilePath As String

    ' Properties we are interested in: "SendUsingAccount" / "SentOnBehalfOfName"
    ' Both get fired when the 'From' field is changed/re-selected
    ' So we are only going to trigger on one event or we will call the code twice
    If Name = "SentOnBehalfOfName" Then

        ' Delete the current signature
        Call DeleteSignature(myMailItem)

        ' Insert the new signature at the current cursor point
        ' The cursor will be at the point where the old signature was deleted
        signatureName = GetSignatureName(myMailItem.SentOnBehalfOfName)
        signatureFilePath = GetSignatureFilePath(signatureName)
        Call InsertSignature(myMailItem, signatureFilePath)

    End If

    Exit Sub

ErrorCatcher:

    MsgBox Err.Description

End Sub

Private Function DeleteSignature(objMail As MailItem)

    Dim objDoc As Word.Document
    Dim objBkm As Word.Bookmark

    Set objDoc = objMail.GetInspector.WordEditor

    If objDoc.Bookmarks.Exists("_MailAutoSig") Then
        Set objBkm = objDoc.Bookmarks("_MailAutoSig")
        objBkm.Select
        objDoc.Windows(1).Selection.Delete
    End If

End Function

Private Function GetSignatureName(sender As String)

    Select Case sender

        Case "Sender Name 1"
            GetSignatureName = "Signature 1"

        Case "Sender Name 2"
            GetSignatureName = "Signature 2"

        Case Else
            GetSignatureName = "Default"

    End Select


End Function

Private Function GetSignatureFilePath(signatureName As String) As String

    GetSignatureFilePath = Environ("AppData") & "\Microsoft\Signatures\" & signatureName & ".htm"

End Function

Private Function InsertSignature(objMail As MailItem, signatureFilePath As String)

    Dim objDoc As Word.Document
    Dim rngStart As Range
    Dim rngEnd As Range

    Set objDoc = objMail.GetInspector.WordEditor

    Set rngStart = objDoc.Application.Selection.Range
    rngStart.Collapse wdCollapseStart

    Set rngEnd = rngStart.Duplicate
    rngEnd.InsertParagraph

    rngStart.InsertFile signatureFilePath, , , , False
    rngEnd.Characters.Last.Delete

    objDoc.Bookmarks.Add "_MailAutoSig", rngEnd

End Function