Jira Service Management (JSM) 4.18 added a feature where, when a customer mentions another user in a comment from the portal, that user is automatically added as a participant.

• JSM 4.18 release notes

Due to this feature, when an Agent is mentioned in a comment, they receive two emails (one for Jira Notification for mention and the other for Customer Notification). This only happens the first time they are mentioned.

To prevent this, it is necessary to enable the dark feature mentioned in this suggestion:

• JSDSERVER-15278 - Add an option that allows disabling the automatic addition of mentioned users as request participants

It is unclear whether this is the expected behavior or a bug, but the customer would like a way to prevent Agents from receiving two emails through a setting in the Admin UI.