Introduction
Setting up OpenDKIM on AlmaLinux 9 is essential for creating a trusted email server that ensures your emails won’t be marked as spam. In this tutorial, we’ll walk you through the steps of installing and configuring OpenDKIM on AlmaLinux 9.
Who this article is for / Why this article is written
This is a technical article that’s better used for technically inclined business owners or IT technicians working at various companies.
By default, AlmaLinux does not have OpenDKIM in its list of repositories, and support for it has waned since RedHat has decided that presumably their clients are not using. We’ll go through a quick explanation of what’s been going on and why these extra steps are required, and provide instructions on how to get OpenDKIM installed on AlmaLinux 9.
Why you’ll have to jump through extra steps to get OpenDKIM working on AlmaLinux 9
It seems that RedHat continues to remove support for packages that aren’t bringing them business, presumably in order to increase efficiencies.
So, many packages have been moved to the CodeReady Linux Builder (CRB) repository instead.
The CodeReady Builder (CRB) repository is a repository that contains additional packages and software for RHEL (Red Hat Enterprise Linux) and its derivatives, such as CentOS and AlmaLinux. The CRB repository provides development tools and libraries that may not be included in the standard repositories due to licensing or support restrictions.
CodeReady is intended for developers and sysadmins who need additional packages for software development, building, and testing that are not included in the standard RHEL distribution. By enabling the CRB repository, you can access the packages required for installing OpenDKIM.
Enable the necessary repositories
First, you’ll need to enable the EPEL repository by running:
dnf install epel-releaseThen you’ll have to enable the CodeReady builder repository:
dnf config-manager –set-enabled crb
Then you’ll need to install both OpenDKIM and the related tools package for it:
dnf install opendkim opendkim-toolsGenerate the DKIM key pair
We’ll assume you already know how to use opendkim-genkey commands and will just provide the high-level overview from here on.
Run the opendkim-genkey command to create a DKIM key pair with the proper selector and domain, and save it in the /etc/opendkim/keys/yourdomain.com directory.
Configure OpenDKIM
Edit the /etc/opendkim.conf file to specify the appropriate settings, including the location of the key pair, the domain, the selector, and the required signing options.
Integrate OpenDKIM with Postfix
Add the necessary “milter” (mail filter) configuration lines to /etc/postfix/main.cf to enable the interaction between Postfix and OpenDKIM.
Configure your DNS & RDNS records
Add the necessary TXT records to your domain’s DNS settings for DKIM, DMARC, and SPF. These records help verify your email server’s identity and reduce the likelihood of your emails being marked as spam.
Make sure your server’s RDNS setting is configured properly as well.
Restart the server’s services and test things out
Restart the Postfix and OpenDKIM services, and then test your email server to ensure that it’s correctly signing emails with the DKIM signature.
Conclusion
And that should be it! With this you’ll be on your way to having an email server on AlmaLinux 9 that’s properly configured with OpenDKIM.
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