I again everyone, i have a new problem, maybe i'm so crazy and this could no be posible to resolv, but anyway i'm going to ask you.
I have an email server over linux with sendmail, i have like 400 users, currently i have been detected that someone on internet has been sent email with some of my email users, this is he or she catch an user of my domain and send email sign with our information email@example.com
this bring me troubles because i receive some emails from diverse postmasters that say that firstname.lastname@example.org
has been sent a virus or pornography, and that's not true.
The question is:
Is there any command, configuration, program, etc, that could allow send email just to my user's linux box ? i mean that anyone else can not send email no matter if they use any user with my domain
How can i block users that doesn't exists on my linux box ? I mean, if a user doesn't exists, that he or she receive a message like: email@example.com
needs to be a valid account anyway firstname.lastname@example.org
can't send email.
or something like that.
sorry for my english, i known is not to good but i hope you can help me.