Outlook - Meeting appointment Problem

When you send meeting appointment to someone and you receive following error message :
The following recipient(s) could not be reached:
/O=XYZ/OU=FIRST ADMINISTRATIVE
GROUP/CN=RECIPIENTS/CN=rparmar on 2008/02/20 17:54
The e-mail account does not exist at the organization this
message was sent to. Check the e-mail address, or contact the recipient
directly to find out the correct address.The MTS-ID of the original
message is:c=us;a= ;p=xyz;l=XYZPERSER1-080220085403Z-1384



Then it s delegation issue. Check outlook of the meeting appointment recepient.
Go to Tool -> Options -> delegates and remove delegates to users(in this case rparmar) who no longer exists in active directory.

This will reslove the issue.