sendmail error

[Nina Pham <nina@xxxxxxxxxxx>]

I have the following error messages when I try to sendmail from nonroot user

   WARNING: RunAsUser for MSP ignored, check group ids(egid=501, want=51)
   can not chdir(/var/spool/clientmqueue/): Permission denied
   Program mode requires special privileges, e.g., root or TrustedUser

That happens even though I already put the username(who sends mail to 
the trusted list.
Any ideas?

Thanks