send/receive email within private lan

hi everyone,

i am testing out postfix inside my provate lan. I have 3 machines in there and i have postfix installed and configured on one of the machines.

When i send email within the box itself i am able to receive it. The email is delivered to the mailbox of the other use to whom i sent the test email, but when i send an email from a different machine to this mailserver, the messages always go out of my mailbox to my ISP and not to the machine it was intended to.

I have added the machine name to my /etc/hosts in all the machines, but even then they are being sent out to my ISP. All machine run linux.

any pointers will be really helpful.

Please provide more detail, e.g. names and IP addreses of machines so we can get an idea of what is sending mail to what, how you have configured the machine that is sending the email, etc. etc.

If you're sending the mail from a mail client and your ISP's mail server is set as the outgoing SMTP server, then the mail won't be delivered locally. Your ISP's mail server is the machine doing the DNS lookup, and it doesn't know anything about your local network. It can't see your local /etc/hosts entries.