500 sendmail exit with error message
This error displays an exit status and error message from the sendmail
command. Many errors will be self explanatory. Others will require
looking at the sendmail manual page.
If you are using Roxen Challengertm, you might get an error like this:
ErrorNo email was sent due to an error.
500 sendmail exit 256 with error message
QUERY_required-email=eee: is not an identifier
The solution is to turn off Roxen Challenger CGI