Mail Activity Reminder

This module adds automatic reminder notifications for planned activities. On each activity type (for example "Call" or "To Do"), a new "Reminders" field lets you enter a list of day offsets, such as "5 0" meaning "5 days before the deadline" and "on the deadline day".

A scheduled job runs every hour and looks for activities whose next reminder time has arrived but whose deadline has not yet passed. For each user, all due reminders are grouped into a single email listing the activities that expire soon, with a button to open each related document. The email is sent through the standard Odoo notification system.

• Reminder times are calculated from the deadline date and the user's time zone, so reminders arrive at the right local moment.
• Once a reminder is sent, the activity records when the last reminder was sent, so the same reminder is not sent twice.
• If an activity is already past its deadline, no reminder is sent.
• The activity form shows computed "Next reminder" and "Deadline" dates.

The module touches mail.activity, mail.activity.type and mail.thread, and adds a field to the activity type form. It also adds a notification template and a cron job named "Mail Activity: Reminders".