I am setting up an Email Send Definition using the SOAP API and I want to pass a variable that I can use in the Ampscript in the Email.
In the documentation I can find that this should be done using the parameter Additional on the EmailSendDefinition Object.
However when I add a value to the Additional parameter I get the below non-descriptive error when performing the Create call til API
StatusMessage: A problem occured processing your request.
Can anyone help me how I can use the Additional parameter or some other way to pass a variable through to use in the Ampscript of the email?