Relaying denied SMTP Error

SMTP servers are often configured to allow connections from within a firewall (or originating from the same computer as where the SMTP server is running) to connect and send email without providing username/password authentication. For example, if I am connected to the Internet via a Comcast cable modem, I can send email using Comcast's SMTP server without authentication. However, if I am connected to the Internet via Earthlink, I can still send using Comcast's server, but I must provide SMTP username/password authentication. If I don't, I'll get the "relaying denied" error (or a similar error that effectively means the same thing). Also note: many organizations restrict SMTP traffic by using firewalls that block the SMTP ports. If this is the case, you will not even be able to establish a connection with the SMTP server (if you are blocked by a firewall). A good way to test is to open a DOS window and enter the command "telnet smtp.myserver.com 25". If you get a "hello" response, you are not blocked. However, if there is no response for a long time and eventually the command fails, it means you are blocked from connecting to the SMTP server, or that there is no server at that remote host listening on the SMTP port (25).

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