553 Sender Address Rejected

Please help, I have just taken over as web-master, and first order of the day is to fix our broken registration process.  Here is the message we get:

Persits.MailSender.4 error '800a0006'
553 <webmaster@thepresidio.net>: Sender address rejected: not owned by user mail@thepresidio.net
/forum/functions/functions_send_mail.asp, line 269

I checked the file, and it has this at this line:

Here is the code segment, of which I marked line 269 with an arrow
...
'AspEmail component
        Case "AspEmail"

            'Create the e-mail server object
            Set objAspEmail = Server.CreateObject("Persits.MailSender")

            With objAspEmail
                If strEmailUsername <> "" Then .Username = strEmailUsername
                   If strEmailPassword <> "" Then .Password = strEmailPassword

                'Out going SMTP mail server address
                .Host = strOutgoingMailServer

                'Who the e-mail is from
                .From = strFromEmailAddress
                .FromName = strFromEmailName

                'Who the e-mail is sent to
                .AddAddress strRecipientEmailAddress

                'The subject of the e-mail
                .Subject = strSubject

                'Set the e-mail body format (BodyHTML=HTML Body=Text)
                If blnHTML = True Then .IsHTML = True

                'The main body of the e-mail
                .Body = strEmailBodyMessage & strEmailBodyAppendMessage

                'Send the e-mail
                If NOT strOutgoingMailServer = "" Then .Send     <-- this is line 269
            End With

            'Close the server mail object
            Set objAspEmail = Nothing

I don't know how to fix this, or what do even look for in debugging this problem.  Please help.

Thanks
Tony Pearson
990.tony@gmail.com