DKIM (Domain Keys Identified Mail) is an antifishing and antispam techgnology that ties a digital signature to the emails. Letters with DKIM get into the antispam filters much rarely and have an advantage over normal mail.

DomainKeys uses domain names to authentify the mail senders. DomainKeys also utilizes the existing DNS to transmit the public encryption keys.

In order to use DKIM you need:

  1. A mail server that supports DKIM;
  2. A pair of public and private keys;
  3. DNS records on the domain that is used for DKIM.

How to enable DKIM without a control panel

In order to create the DKIM key online:


  • Enter the domain name and an arbitrary key name (for example, key1);
  • Click Create Keys.
  • Get the public key:2.OpenKey
  • And the private key:3.PrivateKey

Now you need to place the public key as a TXT record on the domain’s NS server, and place the private key on the mail server. 

How to enable DKIM in ISPmanager

  1. Go to Settings > Possibilities
  2. Highlight the line Mail server (SMTP/POP3/IMAP)
  3. Click Change.
  4. Check the OpenDKIM (exim) field
  5. Got to the Domains > Mailing domains:
    1. Double click your domain name;
    2. Check the mark Enable DKIM for the domain;
    3. Click OK
  6. Open the File Manager and go to the folder /etc/exim4/ssl/;
  7. Find the file The contents of the file will look like:
     dkim._domainkey IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrKa4PQCLAbjeDO1QIcfFwtd5GojPl2suLjCJmL6l9Bc7nrRlAlvnLOlQRH2A38UAUwvG3eyln9GbKbK8/Vmyuu+xmhoWpGVP/PkaneMx1c/E0pN35DUK4cVuingeZRZWlLNIkPTRKcNUWuFK4FN2IblA1z1PRUXNCfEWjUMPqkQIDAQAB" ; ----- DKIM key dkim for
  8. Create a new TXT record on your DNS server. Put “dkim._domainkey” as a subdomain name, while the records itself should be the key itself (contents of the quotation marks in the example above).