Hey!
Could you please perform the following steps:
Check if these settings are enabled from your side: User email visibility - Public, Exclude email header - OFF
To find this setting, go to: System > General Configuration > scroll down
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Click on the “Migrate email” button in Debug mode. Check if everything works now.
Debug mode can be opened by a plugin admin following this guide - How to open Debug mode
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If the issue persists, please send us your Jira Logs, which can be extracted by your Jira administrator following this guide - https://confluence.atlassian.com/support/create-a-support-zip-790796819.html
Cheers,
Nikita - Oboard