it seems you can set a workbook’s Azure Information Protection Sensitivity label using this method:
https://www.mrexcel.com/board/excel-articles/change-sensitivity-label-programatically.66/

Function SetSensitivityLabel(WB As Workbook, LblName As String)

  Dim myLabelInfo As Office.LabelInfo
  Dim Context As Variant
  Dim objWorkbook As Workbook
  Dim CurLabelID As String
  
  Dim sPublic As String
  Dim sGeneral As String
  
  Set objWorkbook = ActiveWorkbook
  Set myLabelInfo = objWorkbook.SensitivityLabel.CreateLabelInfo()
  Set Context = CreateObject("Scripting.Dictionary")
  
  sPublic = "788c8a80-3a15-4016-b4c2-fc99999bfa99"
  sGeneral = ""
  
  Select Case LblName
    Case "General"
      CurLabelID = sGeneral
    Case "Public"
      CurLabelID = sPublic
      
  End Select
 
  With myLabelInfo
   .AssignmentMethod = MsoAssignmentMethod.PRIVILEGED     '1
   .ContentBits = 4
   .IsEnabled = True
   .Justification = "Because"                             'Make this whatever you want
   .LabelId = CurLabelID
   .LabelName = LblName
   .SetDate = Now()
  End With

  objWorkbook.SensitivityLabel.SetLabel myLabelInfo, Context

End Function

However, I’d like to do this for an Outlook MailItem created via VBA – not a workbook. Changing objWorkbook to an Outlook MailItem in the Function above doesn’t expose SensitivityLabel.CreateLabelInfo(). Is there any other way to do this? Looking at this other thread (Azure classification using vba), some answers use a draft template, some use SendKeys – both are suboptimal and answers quite old.

Is there any equivalent for Outlook that doesn’t employ these methods?