Configuring SPF Policy Agent for Postfix SMTP Server
SPF (Sender Policy Framework) is a popular email authentication method used to detect email spoofing. By configuring an SPF Policy Agent, we can tell our Postfix SMTP server to check for the SPF record of incoming emails to help detect forged emails.
Here is a step-by-step guide to configuring the SPF Policy Agent for your Postfix SMTP server:
Step 1: Install Required Packages To get started, you will need to install the “postfix-policyd-spf-python” package. You can do this by running the following command:
sudo apt install postfix-policyd-spf-python
Step 2: Configure Postfix Master Process Next, you need to tell Postfix to start the SPF policy daemon when it starts up. To do this, open the Postfix master process configuration file using the following command:
sudo nano /etc/postfix/master.cf
Add the following lines at the end of the file:
policyd-spf unix - n n - 0 spawn user=policyd-spf argv=/usr/bin/policyd-spf
Save and close the file.
Step 3: Configure Postfix Main Configuration File Now, you need to add the SPF policy settings to the Postfix main configuration file. Open the file using the following command:
sudo nano /etc/postfix/main.cf
Append the following lines at the end of the file:
policyd-spf_time_limit = 3600 smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, check_policy_service unix:private/policyd-spf
The first line specifies the SPF policy agent timeout setting. The following lines impose a restriction on incoming emails by rejecting unauthorized email and checking the SPF record.
Save and close the file.
Step 4: Restart Postfix Finally, restart Postfix using the following command:
sudo systemctl restart postfix
Now, your Postfix SMTP server is configured to check for the SPF record of incoming emails. The next time you receive an email from a domain that has a SPF record, you can see the SPF check results in the raw email header. If the sender sent the email from an authorized host, you will see a “Received-SPF: Pass (sender SPF authorized)” header.