cannot get FormIt to send email (banging head against wall)

System Settings (used if property is missing):
emailsender System Setting: [email protected]
site_name System Setting: XXXXX XXXXX
Properties (from parameters, property set, or snippet default properties:
Tpl chunk name:
subject:
to:
fromName:
replyTo:
emailSender:
allowHtml: 1
message:
Final Values (actually used when sending email):
subject: Default Subject
to: [email protected]
fromName: [email protected]
replyTo: [email protected]
emailSender: [email protected]
allowHtml: 1
Message Body: Default Message
Send reported successful

The original message was received at Wed, 18 May 2011 11:03:10 -0700
from localhost.localdomain [127.0.0.1]

  ----- The following addresses had permanent fatal errors -----
<[email protected]>
   (reason: 553 sorry, your mail was administratively denied. (#5.7.1))

  ----- Transcript of session follows -----
... while talking to relay-hosting.secureserver.net.:
>>> MAIL From:<[email protected]> SIZE=992
<<< 553 sorry, your mail was administratively denied. (#5.7.1)
501 5.6.0 Data format error

Final-Recipient: RFC822; [email protected]
Action: failed
Status: 5.1.3
Diagnostic-Code: SMTP; 553 sorry, your mail was administratively denied. (#5.7.1)
Last-Attempt-Date: Wed, 18 May 2011 11:03:10 -0700


---------- Forwarded message ----------
From: "[email protected]" <[email protected]>
To: "[email protected]" <[email protected]>
Date: Wed, 18 May 2011 11:03:10 -0700
Subject: Default Subject
Default Message