How Can I Setup DomainKeys in Plesk?

1. Open and log in to Plesk.
2. Search in the search bar for: “Mail Server settings” and open the tool.
3. For the setting “DomainKeys spam protection”, please check the Box “Allow signing outgoing mail”.
4. Change to the “Mail Settings” of your domain and activate “Use DomainKeys spam protection system to sign outgoing email messages ”, like in the following screenshot:
   
   
5. Then open the “DNS Settings” for the affected Domain. An additional TXT entry for the subdomain: for example “default._domainkey.yourdomain.com” should have appeared.
6. If you are using your Plesk as nameserver, the configuration should be finished now. 
7. If you are using other nameservers for your domain, for example the ones provided by Contabo, you have to copy the data part completely and add an identical record in the zone there. To do so, please log into the Customer Control Panel.
8. Go to the DNS Zone Management.
9. Click the edit button next to the domain you are setting up the DomainKeys for.
10. Please add, like in the following example, a TXT record for the subdomain “default._domainkey.yourdomain.com” with the data part generated by Plesk.
    
11. Add the subdomain “_domainkes.yourdomain.com” with the TXT record: “o=-“. With this last step, the configuration of DomainKeys has been finished.