How do I allow underscores (_) in the domain (after the @) of an email address?
Oracle B2C Service
Underscores are not allowed in the domain portion of email addresses.
The Oracle B2C Service application complies with RFC 5322 and Internet Message Format standards. RFC 5322 specifically states that domains can only contain letters, numbers, hyphens and dots.
While some email addresses, especially outside the United States, may contain underscores, this is not RFC 5322 compliant. Unfortunately it is not possible to workaround this standard through the application.