DKIM records on various mail servers on the single domain are vital in the security and authenticity of emails especially in utilization and exchange of email services like Gmail. Every mail server must have a unique DKIM key to inhibit email spoofing and the correct authentication of the mail. Setting up DKIM individually per mail server in your domain, with a different selector per mail server. Will allow your emails to land more reliably in their recipients inbox and avoid being identified as spam. Together with SPF and DMARC records, this setup has the potential to greatly enhance security and domain reputation of email messages.
What is DKIM?
Prior to exploring the intricacies of DKIM record management, it will be important to examine what DKIM is. DKIM is an email authentication technology that can be used to identify email spoof. It also applies public-key cryptography in the insertion of a digital signature on the outbound emails. This signature is used to confirm that the message has been sent by an authorized server, and that the message has not been modified on its passage.
When you send an email the email message has Got a DKIM signature in the email header. This is calculated using a private key known only to the sending mail server. The mail server of the recipient can then verify that the mail (to which he has sent the public key by using a secure protocol) has not been altered and that it is sent by a real server using the key created on the recipient mail server.
Why Do You Need DKIM Records for Multiple Mail Servers?
Suppose that your domain has several mail servers (one to process transactional emails, one to send marketing emails, and Gmail to communicate with individuals or teams). Each server should have a separate signature DKIM to authorize an email message. In case DKIM records are not properly configured, messages sent by a one server may be put in spam or fail to send. Which impacts your domain reputation.
DKIM and Gmail: How it Works
Gmail is a popular email platform, where you can use your personal domain in order to send emails. Making this work needs your domain to enable DKIM using Google Workspace (previously G Suite). In case you have more than one mail server serving you. Then you would need to set the DKIM appropriately on each so as to make a smooth authentication of emails to each server.
DKIM signature was checked by Gmail to identify that the incoming emails are sent by the right sender. To send several emails on behalf of your domain (i.e., transactional email companies like SendGrid or Mailgun, or your own internal mail servers). Gmail will consider the DKIM record to authenticate the email for all mail servers.
Setting Up Dkim Records for Multiple Mail Servers on One Domain Gmail
In the case of several mail servers, a separate DKIM key is necessary on each server. You can step-by-step set this up this way.
Step 1 Create the DKIM Keys on Each Mail Server
- In case of Google Workspace (Gmail): Google Workspace (including Gmail) have settings on Google Admin console that you will have to use to create a DKIM key.
- Access Google Admin console.
- Got Series > Apps > Google Workspace > Gmail > Authenticate Email.
- You can generate a new DKIM key here. You would get a public key which you would need to entry into your DNS records.
- Other Mail Servers: See instructions of each mail service you use (e.g. SendGrid, Mailgun, etc.) to create DKIM keys. These services will also avail a public key which must be placed in your DNS records.
Step 2: Row Include DKIM Records in the DNS for Your Domain
After obtaining the DKIM public keys of your mail servers, add each to your domain name DNS records.
Step 3: Verify the DNS Propagation
Once you add the DKIMs records, give time to the DNS propagation. It may range within hours (some minutes to 48 hours). Check MXrecord to ensure that your DKIM record is set correctly and available using the tools such as MXToolbox.
- Google Workspace DKIM Record: DKIM record in Gmail will be of form google. Verifying and suppressing errors over DNS Under your DNS settings. Add a TXT record with the given public key by Google.
- Other Mail Servers: In other mail servers the DKIM record will take the de form selector._domainkey.yourdomain.com. Where selector is a unique literal identifier of the DKIM key (usually supplied by the service). Each server will be assigned different selector so as to make emails sent by various servers to be authentifiable.
Your DNS settings should now have several TXT records point to a mail server each and the right DKIM public key.
Step 4: Test DKIM Configuration
After the propagation of the records, test your DKIM configuration by using test messages sent to each of the mail servers, and testing of the DKIM name in the header of the email. Applications such as Google CheckMX or Mail Tester will allow you to test what you are doing is signing your emails properly with the correct DKIM keys.
Best Practices for DKIM Records with Multiple Servers
- Each Mail Server must have a Unique Selector: No conflict between different mail servers must take place on the DKIM selector. Obviously Google.send grid(submitters name) as an example. So Google.send grid(submitters name) and Google.send grid(submitters name): no difference just like Gmail.
- Key Rotation: Rotate your DKIM keys regularly. Others like Gmail support auto key rotation.
- Check Email Deliverability: Once you have implemented DKIM you need to monitor email deliverability. An application, such as Postmark and Sender Score can be used to monitor whether your mails are being labeled as spam or not.
- Be Consistently consistent: Ensure that emails sent by all your email servers are being sent correctly as per the DKIM signatures. Failure by a single server to sign emails may put your domain reputation at stake.
- With DMARC and SPF Records: DMARC (Domain-based Message Authentication, Reporting and Conformance). SPF (Sender Policy Framework) is recommended in combination with DKIM. These records assist in the implementation of the extra levels of email verification and curb the spoofing emails.
Troubleshooting DKIM Issues
- Emails failing to deliver: In case of not delivering emails. Look at the DKIM record to see whether there are any typos or errors. Besides, make certifications that your DNS is fully propagated.
- SPF alignment problems: Check that your DKIM record should be connected with the SPF record due to the prevention of authentication failures.
- Validate your selectors: verify that each mail server is using the correct selector in its DKIM signature.
Conclusion
Setting up Dkim records for multiple mail servers on one domain is vital to the safety and the deliverability of your Gmail. To certify all your mail servers, you can generate a unique DKIM key per server and use it to sign email messages, and add the related records in your DNS configuration to certify that Gmail and other email services will authenticate emails sent by all your mail servers. This will not only enhance your security in terms of email but makes your domain reputation successful as well so that your emails do not end up being marked as spam by the respective recipients.
By using DKIM, Google Workspace, and any non-Google mail server. It is vital to ensure a proper email hygiene is in place so as to protect your communication. Use the best practice and measure your email deliverability regularly to ascertain that your domain is not doubted and safe.
