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From Meetings, go to General, then Weekly Email Reminders.
See who has an assignment for the upcoming period(s) - "This Week" and "Next Week" are tracked independently.
Email manually, or configure independent automatic sending (day, time, congregation timezone) for each of "This Week" and "Next Week".
Meetings > General > Weekly Email Reminders
Midweek Reminders (tm_midweek_change_reminders), Email Weekend Assignments (tm_weekend_change_reminders) for the meeting-specific versions