[CentOS] sendmail security

Wed Sep 20 10:12:10 UTC 2006
abhishek singh <abhishek.rhce at yahoo.co.in>

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

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>

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.
this is the problem.

 i have one solution , but i want to know very easy
way to do that 

--- Feizhou <feizhou at graffiti.net> wrote:

> abhishek singh wrote:
> > hi 
> > all 
> > i am using sendmail mail server, i have configured
> > SASL+TLS+MailScanner+Spamassasin+.Procmail and its
> > working fine, but there is one problem when i am
> doing
> > telnet to my server on 25 port and using "mail
> from "
> > command to send mail by any user like
> abc at gmail.com or
> > any user @mydomain then sendmail is not able to
> verify
> > sending user , so plz help me how can i verify the
> > real sender means i want only my domain real user
> can
> > sendmails .and when i am using mail clients then
> its
> > working fine . prolem is occuring when , when i am
> > doing telnet directly to smtp port to my server
> Did you use AUTH to authenticate yourself?
> Also, from what you say, do you also want to make
> sure that any user who 
> authenticates must use an email address in your
> domain as their return-path?
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