#550 - this error is given when the server you are trying to send the E-Mail to does not recognize or have the user you are trying to email. Usually this is when the email sender has the wrong address, made a typo, or has been given the wrong email address.

#551 - this error is seen when the person you are sending the email to has been dumped by there ISP for spamming or sending unsolicited E-Mail.

#553 - this is given when you try to send email to a wrong or invalid address. Carefully scrutinize the email address you are trying to send to. The email address should be in the following format: username@cointernet.net.

#554 - This error indicates the recipients email mailbox is full therefore making it undeliverable.

#680 - this is an absent dial tone error. The only two things that I know of that can cause this are either there is a problem with the phone line or the way the phone line is wired, or from the wrong modem driver. 99% of the time it is the line. However, if you have just physically changed your modem and get this message, there is probably a driver problem. Contact your computer Guru for further instruction.

#691 - this is usually a wrong password or ID, and possibly both. Re-enter your ID and/or password to see if this cures the problem. If not contact your Internet Service Provider and see if your account is still active. If you are behind on your account payments, they may have cut you off.

#718 - this gives you a password error. This is normally the error given when the Backbone Radius server is offline, not allowing the user to authenticate with the radius server. If you are sure your password is right, wait a few hours and try again. It usually does not take long for a Network to put the radius server back online. If it lasts more than one day, call your Internet Service Provider.