iPhone truncates email for iMessage via Bluetooth MAP

We were doing some investigation to use an Android tablet to receive/send SMS through an iPhone. The iPhone and the Android tablet were connected by bluetooth to use bluetooth MAP protocol to handle SMS. We made it work when we used phone numbers to send SMS from the tablet. But we had a problem when we tried to use a email to send iMessage. In the tablet App we filled the vCard email item with something like l***3@163.com. From both the tablet and iPhone HCI log we can found that the email was passed correctly. But from the iPhone system log, we found that the first two characters was removed (became q****3@163.com). Then it made the sending fail. Does anyone know that why these first two characters are removed? Thanks. My email: l****2@163.com.

[Edited by Moderator]