abhishek singh schrieb: Do not top-post please. >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> > The syntax isn't correct: there has to be no space in between MAIL FROM:<abs at domain.com> >this command is showing Sender is ok while its not >user in my mail server.after that > >rcpt to: <xyz at domain.com> >DATA >jhsjhdf >. >quit > >after this mail is queued for delivery to xyz user and >in this scenario xyz is valid user accound on my mail >server so i want that unkown account for my domain >cant sendmail , so how i will do that , > >when i am sending mail to out side domain without >authentication then everything is ok means any one can >send mail to my domain while he is not user. > > That makes no sense. >this is the problem. > > I do not see "the problem" from above statement. Just understand your question about avoiding to receive mail from faked senders (see below). > i have one solution , but i want to know very easy >way to do that > > http://www.sendmail.org/~ca/email/fake.html Alexander