Anti-Spam for the first Mail server on the Internet

Article Title: Anti-Spam for the first Mail server on the Internet. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
　　 1. Ip address
For some spam senders with fixed ip addresses or fixed ip segments, We can restrict their smtp connections.
　　
Vi tcp. smtp
　　
218.61.128.61: deny
Restrict any smtp connections between machines 218.61.128.61 and my qmail server
Or:
　　
218.61.128.: deny
Disable any smtp connection between machines in the 218.61.128 network segment and my qmail.
Then
　　
Tcprules tcp. smtp. cdb tcp. smtp. tmp <tcp. smtp
Generate a New tcp. smtp. cdb
　　
You can also use iptables to restrict connections to smtp ports.
　　
　　 2. Seal an account
Mainly for some more formal spam senders
　　
Vi/var/qmail/control/badmailfrom
　　
Edit the/var/qmail/control/badmailfrom file (if no new one can be created) and write the rejected email address. Each record is a row, for example:
　　　　　　
123@123.com
　　
In this way, all emails FROM the 123@123.com will be rejected by the mail server.
　　
You can also reject a domain by adding @ test.com to the badmailfrom file, so that all emails from any address of test.com will be rejected by the server.
　　
　　 3. Set the. qmail-default file
Vi/var/qmail/alias/. qmail-default
　　
/Var/vpopmail/bin/vdelivermail ''bounce-no-mailbox
In this way, the spam is sent. If it is a non-existing email address, the email will be automatically sent back and no this mailbox will be notified.
　　
　　 4. Using third-party rbl services is actually using dns anti-query, which can prevent some people from sending spam messages on their own server.
I am using the real-time blacklist technology of the CDL + DNS anti-query method of the anti-spam alliance of China. This service is free of charge. However, after applying for the service, add/usr/local/bin/rblsmtpd to your smtp startup script, as shown below:
　　
#! /Bin/sh
QMAILDUID = qmaild
NOFILESGID = nofiles
　　
/Usr/local/bin/tcpserver-H-R-l 0-t 1-v-p-x/var/vpopmail/etc/tcp. smtp. cdb-u $ QMAILDUID-g $ NOFILESGID 0 smtp/usr/local/bin/rblsmtpd-r restart hostname/var/vpopmail/bin/vchkpw/bin/true/bin/reject 5checkpw/ bin/true 2> & 1 |/var/qmail/bin/splogger smtpd 3 &