The error message is a permanent rejection message. Can you copy and paste the full error message? I'm guessing you typed it in since SMTP was transposed as SMPT. If the error persists the account may have been suspended or disabled. It's also possible that the rejection is that ISP's way of dealing with accounts that are over quota and other cases the email would not able to be delivered if they accepted it. Try calling the person you are trying to reach to find out if they are having a problem with their email or have a new email address.