Coinbase IPN test page not posting data? On Coinbase under Merchant Profile I'm entering the URL:
https://www.scirra.com/handlers/coinbasecallback.ashx

For the IPN tester.  This ashx page has the code:

var r = "";
foreach(string name in context.Request.Form)
{
    r +=(name + " = " + context.Request.Form[name] + "&lt;br&gt;&lt;br&gt;");
}
r += "&lt;br&gt;&lt;br&gt;" + context.Request.QueryString;
Amazon.Emailer.SendEmail("xxx@domain.com","xxx@domain.com","Callback Dat", r);


The email I receive contains absolutely no data, although the logs page on Coinbase implies it's posting JSON data and returning HTTP 200 (success).

Am I doing something wrong?  Or is this a broken feature?  Can I (semi) safely assume that it posts the JSON in live mode?  And if so, do I simply Request.Form[0] to retrieve it or does it have a string index?

Thanks for any help!
Instant Payment Notification callbacks are POSTed in the form of JSON data.  The issue may be that you're attempting to iterate over regular http params that aren't there, instead of parsing the response body as JSON.  I've never used ASP.net before but this topic looks like it may help:

https://stackoverflow.com/questions/3398926/how-to-retrieve-json-via-asp-net-context-request/3411775