sendmail problem

[Michael Sullivan]

OK.  I can access access port 110, but when I try to send mail from this
address to michael at espersunited.com (my primary email address under my
domain) the mail gets returned with this error:

Each of the following recipients was rejected by a remote mail server.
The reasons given by the server are included to help you determine why
each recipient was rejected.

    Recipient: <michael at espersunited.com>
    Reason:    5.7.1 <michael at espersunited.com>... Relaying denied.
Proper authentication required.

Also, whenever I try to send email from michael at espersunited.com I get
this error: 

Unable to authenticate to SMTP server.
Bad authentication response from server.


Please enter the SMTP password for michael at smtp.espersunited.com

I changed the password in the text box to the password I use on the
client PC, but it won't accept it.  Mail worked just fine on my server
PC (until it went down due to hardware problems), which was running
RH9.  I made nightly backups of the /etc directory on the server PC. 
Then I backed up /etc/mail on my client PC (which runs Fedora Core 1)
and extracted the server PC's backed up /etc/mail files into my client's
/etc/mail.  What am I doing wrong?  Can anyone help me with this?

-Michael Sullivan-