Problems occur While sending mail with attachment on my web hosting server

Question

hi friends,
               hi created one website, am sending mail with attachment on my hosting server. I getting following error:
but sending mail with attachment working in local host. What settings i have to do. please help me.

Security Exception

Description: The application attempted to perform an operation not allowed by the security policy.  To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.

Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.