How to customize Email notification "FYI: Supplier Contact User Account for <Company> was created"

Summary:

When we create the Supplier Portal account for new or existing supplier contact with predefined roles, the Supplier contact receives an email notification with Subject "FYI: Supplier Contact User Account for <Company> was created".

We have a requirement to edit content/email body and email subject of this Email notification.

We have also tried customizing this notification through custom sandbox creation. But no changes made in the sandbox was reflecting in the instance. There are no seeded reports available to customize as well.

We want to know if the customization to this notification is feasible.

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