Interns are generally college students. If the quality of their work is satisfactory, they could be absorbed as permanent employees. Generally they are given designations that is at the lowest end of the organisational hierarchy.
Salaries at various categories are fixed. Generally negotiations do not happen for the lower level. Salary negotiations happen for the experienced persons or those who have very specialised skill set. Now please explain why things come to such a pass where you had to "negotiate" salary with the intern who is nothing but novice? Secondly, why things come to such a pass where you had to "send mail" to intern? Could you call him to your office and discuss about offering permanent job? Is the intern from very hi-fi technical or management institute where he/she has some commanding power?
5th May 2016 From India, Bangalore