If you qmail-smtpd under tcpserver, the following will update relay allow and relay forbid rules.

Create a file called /etc/tcp.smtp and put in it:

127.:allow,RELAYCLIENT=""
1.1.1.1:allow,RELAYCLIENT=""
2.2.:allow,RELAYCLIENT=""
2.2.2.5:deny

Qmail uses simple pattern matching so only classful subnets are allowed. Sorry, no CIDR notation.

The example above will allow/deny:

• Allow relaying from 127.* your localhost subnet of 127.0.0.0/8
• Allow the /32 address of 1.1.1.1
• Allow 2.2.* the /16 subnet of 2.2.0.0/16
• Specifically forbid 2.2.2.5

In order to implement these rules you need to update the server tcp.smpt.cbd file and restart Qmail.

First, back up /etc/tcp.smtp, then run the command:
tcprules /etc/tcp.smtp.cdb /etc/tcp.smtp.tmp < /etc/tcp.smtp

If the rules don’t update, make sure -x /etc/tcp.smtp.cdb is after tcpserver in your start script, then restart Qmail.

Did you find this post useful or have questions or comments?  Please let me know!

The fastest way to deny based on RBL is to add it to whatever ACL you specify in acl_smtp_rcpt

However, you MUST put the declaration AFTER any relay allow definitions. ACLs are based on first-match which means they run in order and stop when they hit a match. Implicit allow.

Here is my ACL declared as acl_check_rcpt

acl_check_rcpt:
  accept  hosts = :
  deny    local_parts   = ^.*[@%!/|] : ^\\.
  accept  local_parts   = postmaster
          domains       = +local_domains
  require verify        = sender
  accept  domains       = +local_domains
          endpass
          message       = unknown user
          verify        = recipient
  accept  domains       = +relay_to_domains
          endpass
          message       = unrouteable address
          verify        = recipient
  accept  hosts         = +relay_from_hosts
  accept  authenticated = *
  deny    dnslists = zen.spamhaus.org
          message = Message rejected because $sender_fullhost is blacklisted at $dnslist_domain see $dnslist_text
  deny    message       = relay not permitted

The RBL definition is toward the bottom, after we allow everyone in that we want in. This lets people relay via SMTP-AUTH or explicit allow before checking the RBL. If they aren’t allowed via anything we allow, then we check the RBL and die with a nice message.

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http://www.postfix.org/VIRTUAL_README.html

Qmail does not allow you to restrict max recipients or max messages per session. I saw reference to a plugin to handle these controls, but do not know the name of it.

You can restrict max message size in /va/qmail/control/databytes

Example:

$ cat /var/qmail/control/databytes
10485760

That’s a 10MB limit

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Example:

example1.com:10.0.0.1
example1.com:10.0.0.2

Will send mail only to 10.0.0.1 The second entry will be ignored.

You are better off using round-robin DNS or submitting a patch to handle priority routing.

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