diff -ur roundup-old/roundup/roundupdb.py roundup-new/roundup/roundupdb.py
--- roundup-old/roundup/roundupdb.py	2017-04-01 14:32:01 -0600
+++ roundup-new/roundup/roundupdb.py	2017-04-01 14:34:24 -0600
@@ -658,7 +658,8 @@
                 if message.get ('In-Reply-To'):
                     send_msg ['In-Reply-To'] = message ['In-Reply-To']
 
-            mailer.smtp_send(sendto, send_msg.as_string())
+            if sendto:
+                mailer.smtp_send(sendto, send_msg.as_string())
             if first:
                 if crypt:
                     # send individual bcc mails, otherwise receivers can