In its wisdom, Wordpress has a long list of common keys that you're not allowed to use in your GET or POST data.
Unfortunately, Mailchimp uses some of these terms which results in a 404 error and the webhook not being processed.
I'm working on a work-around for this problem now, but it's not going to be pretty and will probably cause problems on cheap/restricted hosting platforms. Problem is that by the time any extension code is executed the damage has already been done, so I'll have to write a raw PHP script that wraps the payload and does an internal cURL request or such to forward the data.
In its wisdom, Wordpress has a long list of common keys that you're not allowed to use in your GET or POST data.
Unfortunately, Mailchimp uses some of these terms which results in a 404 error and the webhook not being processed.
I'm working on a work-around for this problem now, but it's not going to be pretty and will probably cause problems on cheap/restricted hosting platforms. Problem is that by the time any extension code is executed the damage has already been done, so I'll have to write a raw PHP script that wraps the payload and does an internal cURL request or such to forward the data.