Dear Group.

I had another issue. I created a web site called www.postbox.com<http://www.postbox.com>, let me say it have the ip address 192.168.0.10 <http://192.168.0.10> . With a dns server running on it. I need to setup a mailserver called mail.postbox.com <http://mail.postbox.com> which must be running on a remote system(same network) and its IP number must be 192.168.0.20<http://192.168.0.20> .

So in the postbox.com{in its dns} , I had made the MX bit as 192.168.0.20<http://192.168.0.20>so when I type

[root@shyam root]# ping mail.postbox.com <http://mail.postbox.com> it is working properly.

I had add /etc/courier/hosteddomains the entry mail.postbox.com<http://mail.postbox.com>

My login id must be shy...@postbox.com,for this I am using mysql authentication.and it works. I can send to mail to my other domain to the mail id shy...@otherbox.com. But the real problem is when I make a reply from shy...@otherbox.com it wont reach the shy...@postbox.com and it will remail in the mailque. When I check the log it shows the error in /var/log/maillog

450 Service temporarily unavailable.

What I understand is that when the mail is sending from shyam@otherbox.comto shy...@postbox.com,courier will be searching for the domain postbox.com<http://postbox.com>which orginally have the ip 192.168.0.10 <http://192.168.0.10>, and it fail to delever the mail since my actuall smtp is running on mail.postbox.com <http://mail.postbox.com> which is running on 192.168.0.20 <http://192.168.0.20>.

In this situation how could I make this kind of approch to work. Is there any kind of aliasing possible. Please do correct me, actually I am very new in mailserver/dns configurations.

Thanks and Regards Shyam