Authentication Token

Hi,

I am trying to retrieve the signer authentication token to build the SignInUrl to be used in Iframe in our application, which we are working on. 

I am trying to use the approach of creating SignerSession with Signer Authentication Tokens as per the below blogs

I am getting a 401 error when requesting an authentication token for a "SENDER" with a mixed-case email. Other places in the REST API do not require a lowercase value for email in the json.

The request I made was:

https://sandbox.esignlive.com/apitoken/clientApp/accessToken
{"clientId":"xxxxxxxxxx","secret":"xxxxxxxxxxx","type":"SENDER","email":"[email protected]"}