Overview

You can set to have your Buyers or Project Managers emailed a reminder to GRN (receipt) their deliveries. To enable this feature, head to Business > Settings > Validations
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Setup

At the bottom of this page is the GRN reminder section as show below: 
Enable the feature and then set the schedule. The only choice is whether to notify the Originator of the order or the Project Manager. If you set Project Manager and an order has no related project, the originator will be notified instead.