service/forum.md

@@ -169,6 +169,21 @@ the discourse PostgreSQL database:
 
     sudo -u postgres psql discourse
 
+## Mass-disable email digests
+
+If a user's account email address stops working (eg. domain becomes
+unregistered), and email digests are enabled (the default) Discourse will keep
+attempting to send those emails forever, and the delivery of each single email
+will be retried dozens of times, even if the chance of delivery is zero.
+
+To disable those emails, this code can be used in the rails console:
+
+    users=User.all.select { |u| u.email.match('example.com') }
+    users.each do |u|
+      u.user_option.email_digests = false
+      u.user_option.save
+    end
+
 ## Pager playbook
 
 ### Email issues