I have been creating a list in my HTML form and kept getting errors that '0' or '1' was not a valid email list to subscribe to. Later I find out that a default email list number was a 10 digit number! How can I see the actual ID number associated with each email list in my account settings? This is not very intuitive unless you know a way I can retreive the list in an HTML form when submitting to the addOrUpdateContact.php example in your API. Remember I want to create a simple form in HTML not PHP or anything else.
I want to start by apologizing for the delay in getting back to you on this! With the recent upgrade of our contact management platform, there was a change made that assigns every list a unique identifier, rather than beginning incrementally with an ID of 1. If you have an API key and access token already, you can use them with the "Retireve a collection of ContactLists" method on our I/O Docs page. This will give you all of your lists with their name and unique ID.
If there is anything more that we can do to help, please let us know!