Hola carlos fijate con este código, se puede mejorar un poco mas las expresiones regulares pero bueno queda en tus manos
Agrega un CommandButton,un ListBox y un Text1
Option Explicit
Function ExtraerEmail(ByVal sURL As String) As Boolean
On Error GoTo ErrFuntion
Dim obj_Expresion As Object, Match, Matches
Dim HtmlDOC As Object
Dim sHtml As String
Dim oXMLHTTP As Object
Set oXMLHTTP = CreateObject("Microsoft.XMLHTTP")
oXMLHTTP.Open "GET", Text1.Text, False
oXMLHTTP.Send
Set HtmlDOC = CreateObject("htmlfile_FullWindowEmbed")
HtmlDOC.body.innerHTML = oXMLHTTP.responseText
Set obj_Expresion = CreateObject("vbscript.regexp")
obj_Expresion.Pattern = "[^,;\s]+@[^,;\s]+"
obj_Expresion.IgnoreCase = True
obj_Expresion.Global = True
Set Matches = obj_Expresion.Execute(HtmlDOC.body.innerText)
For Each Match In Matches
List1.AddItem Match.Value
Next
ExtraerEmail = True
Exit Function
ErrFuntion:
End Function
Private Sub Command1_Click()
Call ExtraerEmail(Text1)
End Sub