Deixando registrado aqui o código de uma necessidade pontual.
;-)
Sub CapturarAtributoTag()
Dim objMail As Outlook.MailItem
Set objMail = Application.ActiveExplorer.
Dim objHTMLDoc As MSHTML.HTMLDocument
Set objHTMLDoc = New MSHTML.HTMLDocument
objHTMLDoc.body.innerHTML = objMail.HTMLBody
Dim objImg As MSHTML.HTMLImg
Set objImg = objHTMLDoc.
MsgBox objImg.getAttribute("src")
End Sub