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An ‘updated reservation’ email will be sent out only if something relevant has changed on the reservation, such as the start or end time, or the resource in which the reservation takes place:
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By default, this flow will send out the email template named Reservation Details for new reservations, and Reservation Updated for changed reservations. If you want to change the text of the emails being sent, you can simply edit the contents of these email templates. If you want to use different email templates, you can edit the two ‘set template for new/updated reservation’ assignments:
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