meglio ancora sarebbe metterci questo:
codice:
Dim Visited As Boolean

Private Sub Form_Load()
Visited = false
Label1.forecolor = &H0000FF
End Sub

Private sub Label1_Click()
Shell ("explorer mailto:indirizzo@indirizzo.in")
Visited = True
End Sub

Private sub Label1_MouseMove(...)
Label1.Forecolor = &Hff0000
End Sub

Private Sub Form_MouseMove(...)
If Visited = False Then
    Label1.Forecolor = &H0000FF
Else
    Label1.ForeColor = &H880088
End if
End sub
magari modificando i colori