Les Mikesell wrote: > On Wed, 2006-09-20 at 05:12, abhishek singh wrote: > >> yes i am using SMTP Authentication , but when i m >> doing telnet to my server on 25 port so i am able to >> send mail by unknow user that in in not my mail server >> like >> >> >> mail from: <abs at domain.com> >> >> this command is showing Sender is ok while its not >> user in my mail server.after that >> > > The stock Centos configuration should reject everything > that doesn't come from the localhost unless you make > changes to /etc/mail/access to permit it. Are you > doing this test from the local host? > > Do you have telnet open to the outside world? If so kill it and only allow ssh with the proper extra security setup. You may need to open telnet for a little while for testing purposes, but don't leave it that way. John Hinton