1. The merge of the "email_template" module into the "mail" module.
2. The send action of the mass mailing has been moved from the frontend to a cron, because it was too slow to send over 10,000 mails (the user's browser was blocked for 15 - 20 minutes). Mass mailings have now their own process in the kanban view.
3. Mails sent from the mail form are sent immediatly instead of from the mail queue (for instance, when you go to sales > customers > list view > select 2 -3 customers > More > Partner Mass Mailing).
4. Users have now the choice from which mailing list they want to unsubscribe when they click on the unsubscribe link at the bottom of the mail.
5. Mass mailings inherit from their campaign UTMs and mass mailing campaigns are linked to an UTM campaign.
6. Many little improvements
This commit adds a way to configure scheduled emails on events. It replaces
existing automatic emails at confirmation and subscription. It proposes to
configure some schedulers, based on subscription or event, using a template
and a configurable timedelta.
A cron is added that regularly checks for event mailing schedulers to execute
and launch them. The granularity of send emails is therefore limited to the
granularity of the cron, aka 1 hour.
[TEST] Added tests for this feature.
Also cleaned a bit event, country_id is now a pure related instead
of a computed field trying to be a related. Also removed default templates
on event category. Configuration in the event itself should be easy
enough for most use cases.
Julien De Coster