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You can choose to enable various entities on the issue for notification (eg Reporter, Assignee etc), there is also support for User/Multi User Picker fields and even Group/Multi Group Picker fields. Combining these settings with to: Delivery Type can have a huge impact on plan usage if not managed carefully.
Inhibiting notifications through the template
JEMHC will render the TemplateSet for the issue notification for each recipient in scope, during that render it is possible for custom markup to drive the current notification (recipient) to be inhibited, see Inhibit notifications based on run-time conditions for more, and Manipulate webhook data in notification templates for how to work with the Webhook event.
Data Volume
There are some great features in JEMHC for including images/attachments in outbound notifications, however, these come at a cost in terms of your Capacity Plan.
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