Fixed imap get_last_message to return positive integer

applications/admin/languages/es.py

@@ -249,6 +249,7 @@
 'new plugin installed': 'nuevo plugin instalado',
 'New plugin installed: web2py.plugin.attachment.w2p': 'New plugin installed: web2py.plugin.attachment.w2p',
 'New plugin installed: web2py.plugin.dialog.w2p': 'New plugin installed: web2py.plugin.dialog.w2p',
+'New plugin installed: web2py.plugin.math2py.w2p': 'New plugin installed: web2py.plugin.math2py.w2p',
 'New Record': 'Registro nuevo',
 'new record inserted': 'nuevo registro insertado',
 'New simple application': 'Nueva aplicación',

gluon/dal.py

@@ -6115,16 +6115,20 @@ class IMAPAdapter(NoSQLAdapter):
 
     def get_last_message(self, tablename):
         last_message = None
-        # request mailbox list to the server
+        # request mailbox list to the server if needed.
-        # if needed
         if not isinstance(self.connection.mailbox_names, dict):
             self.get_mailboxes()
         try:
-            result = self.connection.select(self.connection.mailbox_names[tablename])
+            result = self.connection.select(
+                self.connection.mailbox_names[tablename])
             last_message = int(result[1][0])
+            # Last message must be a positive integer
+            if last_message == 0:
+                last_message = 1
         except (IndexError, ValueError, TypeError, KeyError):
             e = sys.exc_info()[1]
-            LOGGER.debug("Error retrieving the last mailbox sequence number. %s" % str(e))
+            LOGGER.debug("Error retrieving the last mailbox" +
+                         " sequence number. %s" % str(e))
         return last_message
 
     def get_uid_bounds(self, tablename):