Redmine

Confirmed. The reason is that the process doesn't wait for the thread to finish. Adding a simple sleep works but it's not an elegant fix:

Index: app/models/mailer.rb
===================================================================
--- app/models/mailer.rb    (revision 3560)
+++ app/models/mailer.rb    (working copy)
@@ -323,6 +323,7 @@
     issues_by_assignee.each do |assignee, issues|
       deliver_reminder(assignee, issues, days) unless assignee.nil?
     end
+    sleep(10)
   end

   private

Maybe we'd better disable asynchronous sending when sending reminders.

Thanks for investigation.
How about this fix? Waiting for all threads to finish.

Index: app/models/mailer.rb
===================================================================
--- app/models/mailer.rb        (revision 3561)
+++ app/models/mailer.rb        (working copy)
@@ -309,6 +309,7 @@
     issues_by_assignee.each do |assignee, issues|
       deliver_reminder(assignee, issues, days) unless assignee.nil?
     end
+    Thread.list.each {|t| t.join(10) unless t == Thread.current}
   end

   private

Go MAEDA wrote:

Thanks for investigation.
How about this fix? Waiting for all threads to finish.

[...]

Note 19 of #4228 states that it does not work :(

Would be nice if someone could test this change to lib/tasks/email.rake as proposed in #4228 :

task :receive_imap => :environment do
  Thread.abort_on_exception = true
  ...
  (existing code)
  ...
  threads.each {|t| t.join }
end

Etienne, it didnt work for me.

I'm quite sure that this same issue has been causing emails to (sometimes) not be generated in response to email-stimulus (the process-incoming-emails rake task). Drop rate <30%.

I just stumbled upon this issue and finally found out why I never got the reminder emails feature working...

Etienne Massip wrote:

Would be nice if someone could test this change to lib/tasks/email.rake as proposed in #4228 :

[...]

Just tested it, but the same as Serge ST, it isn't working.

Note: I've added a reference to this issue on RedmineReminderEmails and EmailConfiguration.