Hi everyone,
Thanks a lot for your help and suggestions.
The issue is now resolved.
It turns out the root cause was related to the email configuration — the system was missing a properly defined external SMTP relay. Once a working relay was set up and the sender address was aligned with the authenticated user (e.g. noreply@mail.com), everything started working correctly.
This applied to both DocuSeal and another app I tested. One of them required setting environment variables manually to define the SMTP parameters explicitly.
Appreciate the time you took to respond. Hopefully this helps others who might encounter the same situation.
Thanks again to [@james] and [@luckow] for your support — and hopefully this can help someone else who runs into a similar case in the future.
Best,
saivie