Hi all,
I know that qmail can control the policy at /var/qmail/control/* such as badmailfrom, badmailto rcpthost blabla... Badmailto can be used to list a deny mail account. But it is a lot of account that spammers can create. For example:
my domain is test.com and user mail account is abc@test.com.
The question is how can i block all unregistered account and allow only listed account.

There is a patch for qmail that does does that. It's called chkuser. It's been so long since I setup my server I couldn't begin to tell you how it works though. But there is a number of toasters like the one at http://www.shupp.org/toaster/ that includes it.

And yeah, I recall that was the most annoying thing about qmail...All those dang bounced emails to non-existant usernames.

If you configure qmail to dump mail to non-existant addresses, that problem goes away.There are several ways to do this. There is the chkuser patch, as DaHammer mentioned. There is the goodrcptto patch. There is also a patch that allows you to check for vpopmail virtual users (although, I hear this one is a bit messy and not recommended).

You can search the qmail list archives at http://msgs.securepoint.com/qmail/ for "block unknown address" as a good starting point. Do *NOT* post this question to the qmail list unless you want to get flamed like you have never been flamed before, as it has been posted hundreds of times.

All of the recommended solutions require you to update a file that is consulted on every mail delivery anytime you add a new user. Most folks who use these patches simply script the process of updating the neccesary file.

Personally, I use the goodrcptto patch and a PHP script I wrote run every ten minutes via cron to update the ~qmail/control/moregoodrcpt file. I believe that the goodrcptto patch differs from the chkuser patch in that the goodrcptto patch checks *all* recipients of an email and validates them, whereas the chkuser patch only validates some email addresses (although I could be mistaken about this).

I have setup qmail on 2 boxes with the help of http://www.qmailtoaster.com/centos/c...CentOS-4.3.txt
There are two separate domains running on these boxes. The reason for choosing this is the ease of installation and integration of other mail server related packages. They have been running for now approx a month and a half. One of the boxes is also behind a firewall. Suddenly over the last two days both the boxes failed with the following bounce message to all incoming as well as local mail 'Remote host said: 553 sorry, your envelope sender has been denied (#5.7.1)'. Which means the mail servers have effectively failed.
Since I have little experience with qmailtoaster (have installed and managed vanilla qmail installs) I am at a loss to explain the problem. In my investigation of the same the feeling I get is that chkusr/chkuser seems to be the problem. It is bouncing all mail with the above message. Neither is there much information on the problem when googling for it.
I am in rather dire straits regarding the same.
All help appreciated.