Could you send us more detail. I guess that you are distributing a PDF form that you have imported in FormsCentral. Could you send your file at DL-formscentral_feedback referencing this thread so we can investigate the issue.
Also, to help narrow down the problem, can you try to submit without using the proxy server? (we cannot reproduce the problem with SSL certificate when submitting but don't have the proxy setup, so it's possible related to the proxy).
Do you see any problem when submitting to the form via browser (using form url link)?
Thank you for getting back in touch so quickly. I have further tested this issue and can confirm that if I bypass our proxy server, the submit works without issue. Sadly this therefore pushed the problem to our proxy server.
At present I have set the proxy server to not require authentication for https://adobeformscentral.com, do you know if there are any other sites or specific ports the form submission process utilises?
Thank you again,