How to Set Up DomainKeys Identified Mail (DKIM) for Your Email Server

Setting up DomainKeys Identified Mail (DKIM) is essential for email security and helps to ensure that your emails are not tampered with in transit. It involves a digital signature added to the email’s header, allowing the receiving email server to verify that the email message was indeed sent from your domain and has not been altered. Here’s a step-by-step guide on how to set up DKIM:

1. Check If Your Email Service Provider Supports DKIM

Before you start the setup process, it’s important to check if your email service provider (ESP) supports DKIM. Most modern ESPs like Google Workspace, Microsoft 365, and others support DKIM natively.

2. Generate DKIM Key Pair

You need to generate a public/private key pair for DKIM. The public key will be published in your DNS records, while the private key will be used by your email server to sign outgoing emails.

  • If you’re using an ESP, they will often generate the key pair for you and provide the public key to add to your DNS.
  • If you’re managing your own email server, you may need to use software that can generate these keys, such as OpenSSL, or an online DKIM key generation tool.

3. Add the DKIM Record to Your DNS

Once you have your public key, you need to add it as a TXT record in your domain’s DNS settings. The process will vary depending on your DNS provider or web hosting service, but here are the general steps:

  • Log into your DNS management console.
  • Find the option to add a new TXT record.
  • The record will typically need the following format:
    • Host/Name: This is usually something like selector._domainkey.yourdomain.com, where selector is a unique name identifying the key. Your ESP or key generation tool will provide this.
    • Value: This is where you enter the public key provided by your ESP or generated by your tool. Make sure to format it correctly as per your DNS provider’s instructions, which usually starts with v=DKIM1; k=rsa; p=YOUR_PUBLIC_KEY_HERE without line breaks.

4. Update Email Server or ESP Settings

  • For those using an ESP, you’ll likely need to specify or select the DKIM selector within their interface to complete the process.
  • If you’re running your own email server, configure it to sign outgoing emails with the private key. The precise steps here depend on your server’s email software.

5. Test Your DKIM Setup

After setting up DKIM, it’s crucial to test and ensure it’s working correctly:

  • Use a DKIM validator tool available online by sending an email to a testing service or using tools provided by various online platforms.
  • Check your outgoing emails for a DKIM signature in the email headers.

6. Monitor and Maintain

  • Keep your private keys secure and rotate them periodically for enhanced security.
  • Make sure to update your DNS records with the new public keys whenever you rotate your keys.

Note

The exact steps, especially for generating the key pair and updating your email server settings, can vary greatly depending on the specific software you’re using or the ESP. Always refer to your ESP or software’s official documentation for the most accurate and secure procedures.