ServiceDesk Plus API

Hi!

Trying to use ServiceDesc API (h_ttp://machine_name:Port_Number/servlets/RequestServlet).

My task is:
Unknown users can add new requests through company website. Website was written on php.

I have realized requests to ServiceDesc using CURL, but faced with problem:
User account is created, but without Email, though I'm send it in "requesterEmail" field.

In documentation (h_ttp://[SD_HOST]/SetUpWizard.do?forwardTo=api) this field is described as "Email Id of Requester".

What is it mean? What is "Email ID"?
Please, say me how I can properly create requesters (at least Name and Email need to be filled) using ServiceDesc API?

P.S. Sorry my English.