Why do I get Outlook cannot connect to your outgoing (SMTP) e-mail server?

I am trying to configure Outlook 2007 to work with my IMAP account. I followed the directions on this sight and I can receive mail, but I cannot send mail.

I am using mail.mydomain.com (where mydomain is my actual domain) for both the incoming and outgoing mail servers. I also configured it to indicate that my outgoing server requires authentication and to use the same settings as my incoming server.

Thanks for your assistance.

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