Comment 6 for bug 1130957

OK, I found out where the second error comes from. When there is no administrator available, the message is sent to the site_owner from the configuration file, but this entry is not converted to unicode before being set in the msgdata dict.
Thus, when it's added to the database, Storm refuses it. The following patch fixes this bug:

=== modified file 'src/mailman/handlers/owner_recipients.py'
--- src/mailman/handlers/owner_recipients.py 2013-01-01 14:05:42 +0000
+++ src/mailman/handlers/owner_recipients.py 2013-04-12 16:47:29 +0000
@@ -55,7 +55,7 @@
         # To prevent -owner messages from going into a black hole, if there
         # are no administrators available, the message goes to the site owner.
         if len(recipients) == 0:
- msgdata['recipients'] = set((config.mailman.site_owner,))
+ msgdata['recipients'] = set((unicode(config.mailman.site_owner),))
         else:
             msgdata['recipients'] = recipients
         # Don't decorate these messages with the header/footers. Eventually