The header you entered contains an invalid character, such as ':', a non-printable character, a non-ascii character, or an eight bit ascii character. Please remove the invalid character and try again.
Mae'r pennyn rydych wedi ei roi yn cynnwys nodau annilys, megis ':', nod anargraffadwy, nod nad yw'n ascii, neu nod ascii wyth did. Tynnwch y nod annilys a cheisiwch eto.