in our customers SP2013 enviromment, I experience a problem with Task Delegation via the Web Service method "DelegateTask". With parameter "sendNotification" set to 1, the web service processes the delegation but does not sent an email and returns an error:
<faultstring>Server was unable to process request. ---> Cannot get the full name or e-mail address of user "UserLoginName". ---> Exception of type 'System.ArgumentException' was thrown.
Parameter name: value</faultstring>
while "UserLoginName" is the actual Login Name of the user the task is delgated to.
Any idea what's wrong here? Is there any special configuration to be taken care of?
userLoginName itself is not suffcient, you have to provide user identifier in a form claim|domain\user or his/her mail address directly.