As you probably know, email addresses can be divided into two parts before and after the @ sign as in username@destination. Receiving a "Recipient not known" message usually means that the destination part of the email address you used was correct but the username was incorrect or the users account might have lapsed (or perhaps that you put the right username but sent it to the wrong destination!). Please check that the email address you used is correct or try contacting the person by some other means to verify their email address. If you are sending a message from your Marjon email account to somebody else at Marjon and you are not sure of their email address you can put in their real name and click the "Check Names" button before you send. If the server recognises the name it will automatically add their email address to the message.