Learn how to configure DKIM for Sendmail on Ubuntu. Our Sendmail Support team is here to help you with your questions and concerns.

How to Configure DKIM for Sendmail on Ubuntu: A Beginner’s Tutorial

DKIM is short for DomainKeys Identified Mail. It is a key email authentication method that makes sure our emails are from our domain and haven’t been tampered with.

In fact, it is a key defense against email spoofing. It is used by major email providers to fight spam and phishing. Our experts have put together this guide to help you set up DKIM for your domain.

1. First, install OpenDKIM and the needed tools on the server. Open a terminal and run:

   sudo apt-get install opendkim opendkim-toolsCopy Code
2. Next, create a directory to store the domain’s DKIM keys. Replace `DOMAIN.COM` with the actual domain name:

   sudo mkdir -p /etc/opendkim/keys/DOMAIN.COMCopy Code
3. Then, generate the DKIM keys as seen here:

   sudo opendkim-genkey -D /etc/opendkim/keys/DOMAIN.COM -d DOMAIN.COM -s defaultCopy Code

   So, this will create two files in the specified directory: `default.private` (the private key) and `default.txt` (the public key).
4. Next, make sure the permissions are correctly set for the key files:

   sudo chown -R opendkim:opendkim /etc/opendkim/keys/DOMAIN.COM
   sudo chmod 640 /etc/opendkim/keys/DOMAIN.COM/default.private
   sudo chmod 644 /etc/opendkim/keys/DOMAIN.COM/default.txt
   Copy Code
5. Now, it is time to edit the OpenDKIM configuration file (/etc/opendkim.conf) and add these lines. Also. replacing `DOMAIN.COM` with your actual domain:

   
   Domain            DOMAIN.COM
   KeyFile            /etc/opendkim/keys/DOMAIN.COM/default.private
   Selector           default
   Copy Code
6. Then, edit the OpenDKIM default settings and add this line to specify the socket:

   SOCKET="inet:8891@localhost"Copy Code
7. Now, edit the Sendmail configuration file and add the following line to the configuration:

   INPUT_MAIL_FILTER(`opendkim', `S=inet:8891@localhost')Copy Code
8. Also, rebuild the Sendmail configuration and restart the services:

   sudo sendmailconfig
   sudo service sendmail restart
   sudo service opendkim start
   Copy Code

After following these steps, our Sendmail should be configured to sign outgoing emails with DKIM. This will make sure our emails are authenticated and secure.

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Conclusion

In brief, our Support Experts demonstrated how to configure DKIM for Sendmail on Ubuntu.