Hi,
Few questions for you
1. Are you are super user or do you have Email-Admin rights?
2. Can you tell me what is Localization and version of your Business Central tenant?
3. Do you have any customization done on this module?
- if yes then kindly uninstall the extension and try again
I tried to send the PO in mail and it worked in US tenant with version 20.2
If my answer was helpful to you, please verify it so that other users know it worked. Thank you very much