Register for Event using URL API (AT=EN) - redirect fails?

I am trying to send a user registration for an event into WebEx using a form POST.  The registration is actually working, it shows up in the system and receives a configured followup email. However instead of redirecting back to my thankyou page, the system is generating an error message stating:

"The URL's domain has been blocked. Contact your site administrator for more details."

The URL for that page looks like:

https://nope.webex.com/cmp0401lsp13/webcomponents/widget/invaliddomain.do?siteurl=nope&domainname=www.myserver.com&AT=EN&ST=SUCCESS&EI=358976

The form looks like:

<form name="register" id="webex-register" method="post" action="https://nope.webex.com/nope/m.php" style="margin: 3rem auto;">

    <input type="hidden" name="AT" value="EN"/>

    <input type="hidden" name="MK" value="1234"/>

    <input type="hidden" name="AE" value="myaddress@nope.com"/>

    <input type="hidden" name="FN" value="John"/>

    <input type="hidden" name="LN" value="Doe"/>

    <input type="hidden" name="CO" value="Some Compnay"/>

    <input type="hidden" name="TI" value="Some position"/>

    <input type="hidden" name="A1" value="123 Main St."/>

    <input type="hidden" name="A2" value="Suite 2"/>

    <input type="hidden" name="CY" value="Atlanta"/>

    <input type="hidden" name="ST" value="Georgia"/>

    <input type="hidden" name="ZP" value="30309"/>

    <input type="hidden" name="CR" value="United States"/>

    <input type="hidden" name="PN" value="555-5555555"/>

    <input type="hidden" name="SM" value="1"/>

    <input type="hidden" name="BU" value="https://www.myserver.com/webx/thanks"/>

    <input type="submit" value="Register Now">

</form>

I have been unable to find any documention for this error message or for EI=358976 but then I'm very new to the WebEx APIs so I could be looking in the wrong places.

I can't use the XML API.

Greetings! The message you are receiving is being generated when we try and access the URL you have listed as the BU value:

     <input type="hidden" name="BU" value="https://www.myserver.com/webx/thanks"/>

Are you able to directly access that exact value (i.e. copy-and-paste what you have in the BU field into a browser)?

Thanks for the reply Michael.

Of course I tested various actions with the BU URL and made sure that I could load it directly.

I found that as I suspected, the issue was that our instance of WebEx was configured via a third party so we did not have an actual 'super admin' account and can not see any of the configuration settings.  There is a white list setting (NOT discussed in the URL API docs) the setting is apparently called "Enforce BACKURL domain names" and additionally there is a setting to place the BACKURL domains into a white list.  Once this was done, the redirect worked as expected.

I was on vacation for a while, and then got pulled into some other unrelated projects so I forgot that I had been intending to reply here in case anyone else sees this.

I can see where the XML API is more powerful and in most cases, e.g. for server-to-server would be prefered; however the URL API turned out great in this case for scraping data out of another SaaS system and pushing the user registration into WebEx.  It just seems that the white listing parameters should be mentioned in the API doc file.

Hi Robert,

I'm not able to find this in settings.  Can you show me where it is in Webex admin?

This option can be disabled and hidden depending on site configuration, reach out to your Customer Service rep to have this option enabled on your site if it is not already.

Spoke to a support rep who directed me to do this:

1. Click the "configuration" on the left side -->common site setting --> option

2. Scroll down to the last part of the page to " Allow the following URL domain names: webex.com "   in that add your Marketo subdomain and check

3. Click update

We did that, but now the link in the webinar confirmation email doesn't go to the WebEx event page, it goes to the BU URL instead.