It is not a good idea to publically display your email or indeed someone else's email address in a public forum. When you get a mailor daemon response from the server it tells you what is wrong. If you get error messages or a mailor daemon response, you would need to include the entire message word for word without disclosing the part before the @ in an email address, otherwise how can anyone know exactly what it reported. One possibility: If her email account is completely full of emails then the quota limit may have occured in which case the server physically cannot receive any more emails until that person deleted some emails to make space.