Helpdesk users can receive notifications about events in Helpdesk issues. Notifications include links on Helpdesk issues and attachments which can be uploaded without login JIRA.
We recommend to set Jira's project notification scheme to None and use only notification scheme in Helpdesk Notifications settings with "Use Jira project notifications for Jira users" enabled to send Jira notifications to Jira users and HelpDesk notifications to HelpDesk users.
Otherwise you can set recomend to set 2 different Notifications schema for your HD projects:
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