Error when attaching file using clr in sqlserver

I have a scalar function in sql server which is using a clr for attaching file while sending mail using the sql procedure "MSDB.DBO.SP_SEND_DBMAIL ".

I am getting the below error whenever I am trying to send mail.

"The client connection security context could not be impersonated. Attaching files require an integrated client login".


Please help to resolve the issue.