Email regex does not recognize punycode

As per HTML standards, user agents should convert punycode in the domain labels of the value to IDN in the display and vice versa. See https://html.spec.whatwg.org/multipage/input.html#email-state-(type=email)
phpBB regex does not recognize digits and dashes in punycode converted IDN email addresses, in 1st domain level in particular, f.e. admin@xn-b1agh1afp.xn-p1ai when set as "Contact email address" or "From email address" causes "The email address you entered is invalid." error in ACP.