How to check if DKIM is working on a domain in Plesk

Question

How to check if DKIM is working on a domain?

Answer

 

Verifying DKIM setup on a Plesk server

1. Log in to Plesk.

2. Verify that DKIM is enabled in server-wide setting at Tool & Settings > Mail Server Settings.

   

3. Verify that DKIM spam protection system is enabled for a domain at Domains > Mail Settings.
   

   

4. Verify that DNS TXT records in domain's DNS zone exist at Domains > DNS Settings or on external DNS server:

   default._domainkey.example.com
   _domainkey.example.com

   

5. Using the "nslookup" utility (works both on Linux and Windows in a command prompt), verify that the records from step 3 have been propagated to the Internet. Replace example.com with your domain name:

   C:> nslookup -q=TXT default._domainkey.example.com 8.8.8.8
   Server: 8.8.8.8
   Address: 8.8.8.8#53

   default._domainkey.example.com text = "v=DKIM1; p=<DOMAIN'S_DKIM_KEY>"

   C:> nslookup -q=TXT _domainkey.example.com 8.8.8.8
   Server: 8.8.8.8
   Address: 8.8.8.8#53

   _domainkey.example.com text = "o=-"

   • 8.8.8.8 here is a Google Public DNS.

 

When sending an email to external mail services (Gmail, Outlook, etc)

1. Send an email from an email account on your domain to external mail service.

2. On external mail service, open email header and verify that there is a record dkim=pass in Authentication-Results header section:

   • Authentication-Results: mx.google.com; dkim=pass header.i=@example.com; spf=pass (google.com: domain of john.doe@example.com designates 203.0.113.2 as permitted sender) smtp.mailfrom=john.doe@example.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=example.com

 

If all the steps are met, DKIM is working fine on the domain.