diff --git a/bitmessagemain.py b/bitmessagemain.py
index c1ab7043..51c8b210 100644
--- a/bitmessagemain.py
+++ b/bitmessagemain.py
@@ -3377,6 +3377,12 @@ class MyForm(QtGui.QMainWindow):
                             self.statusBar().showMessage('Error: The address '+ toAddress+ ' contains invalid characters. Please check it.')
                         if status == 'versiontoohigh':
                             self.statusBar().showMessage('Error: The address version in '+ toAddress+ ' is too high. Either you need to upgrade your Bitmessage software or your acquaintance is being clever.')
+                        if addressVersionNumber > 2 or addressVersionNumber == 0:
+                            QMessageBox.about(self, "Address version number", "Concerning the address "+toAddress+", Bitmessage cannot understand address version numbers of "+addressVersionNumber+". Perhaps upgrade Bitmessage to the latest version.")
+                            continue
+                        if streamNumber > 1 or streamNumber == 0:
+                            QMessageBox.about(self, "Stream number", "Concerning the address "+toAddress+", Bitmessage cannot handle stream numbers of "+addressVersionNumber+". Perhaps upgrade Bitmessage to the latest version.")
+                            continue
                     elif fromAddress == '':
                         self.statusBar().showMessage('Error: You must specify a From address. If you don''t have one, go to the ''Your Identities'' tab.')
                     else: