Updates the signature image for an accountless signer. The supported image formats for this file are: gif, png, jpeg, and bmp. The file size must be less than 200K.
For the Authentication/Authorization for this call, the credentials must match the sender of the envelope, the recipient must be an accountless signer or in person signer. The account must have the
CanSendEnvelope property set to true and the
ExpressSendOnly property in
SendingUser structure must be set to false.
The external account number (int) or account ID GUID.
The envelope's GUID. (For example,