After importing your external users with CSV as explained in this page, you can import them to Jira Service Management as Customers. Users imported as Customers do not have any product access, but they can only access to the service management portals.
To achieve that, you need to first create a group with only one product access: Jira Service Management, and their product role should be “Customer”.
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After creating the group, select the users you want to give customer access to Jira Service Management. Click on the operations icon and select “Add as customer”.
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You will be asked to provide a group. Select the group that you have just created with Customer role access to Jira Service Management. Then, click on Next. You customers will be created shortly after.
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