- A Cloud Guru
Postfix with Greylisting
In this lab, you will be provided with a Linux CentOS server that has Postfix and greylisting installed but not configured. Your task is to configure the software so that incoming emails are sent through the greylisting process. The purpose of this lab is to have you configure Postfix to use the greylisting policy. Once configured, you will verify that Postfix is directing incoming email through the greylisting process.
Table of Contents
Log In to the Provided Server
Log in to the server as
cloud_userwith the provided password.When the
SERVER-READYfile is shown in the
/home/cloud_userfolder, you can then follow along with the tasks.
Install the Postgrey Greylisting Software
yumsystem commands, install the
postgreypackage. Start the software and set it to auto-start on system reboot.
Configure the Postfix Configuration File to Use the Postgrey Service
/etc/postfix/main.cffile and add the Postgrey policy service so incoming emails get greylisted on arrival.
Restart the Postfix email server.
Test That Postgrey Is Intercepting Emails
Test that the Postfix service is using Postgrey to intercept emails.
When testing, you should see a Recipient address rejected message.
When you retry after 60 seconds, the email should now be accepted.
An example of using the
telnetprogram to connect to a local email system is as follows:
telnet localhost 25 ehlo localhost mail from: cloud_user rcpt to: testuser
At this time, you should see a message saying you have been greylisted for 60 seconds.
Wait 60 seconds and try the command again:
rcpt to: testuser
This should allow you to continue with the task of sending email data.
Now you can test by using the
sucommand to sudo to the
testuserand checking email.
su - testuser mailx
This should show you your email.
What's a lab?
Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.