After reading the forum I am not hopeful that this can be done in any useful way, but here goes...
Here is my process so far...
I have a web page that colects certain information relevant to a conference (www.segfa.org/upcoming.php if you want to play along)
The user fills out the information on their name, company, how many people, the events they are attending etc.
They click on continue, which takes them to a page that calculates the total amount, stores the information in a record in the relevant phpMySQL database table online, and creates the button using the SIM method to pass the payment information to Authorize.net
The problem is, some naughty people are completing the form, but not paying after clicking the button. The system has no way of telling, without manually chasing down every payment, which ones have completed the transaction.
So what I want to do, like PayPal does, is include a successful payment redirect location (succes.php?ID=12345 for example) that would automatically send them back to the web site. This would then send the email AFTER processing the payment rather than before payment is received.
I think it can be done using relay response, but can I pass the unique ID number from the data back to the web page using relay response, or is there no way of making it dynamic?
I tried to find a good tutorial on here about relay response, but it all seemed so technical, and I don;t want to dive all the way in until I know it can do what I need it to :)
Thanks for any advice.