Mail signing protocols, such as DomainKeys and DKIM signing, verify the authenticity of a message and can be used to protect users from phishing schemes or spam attacks.
Signing messages with DomainKeys has been removed as that signing method has become obsolete. Follow these steps to set up DKIM:
1. Log into SmarterMail as the Domain Administrator--postmaster account,click the Settings icon,expand the Domain Settings and Advanced Settings folders in the navigation pane.
2. Click Mail Signing. The mail signing settings will load in the content pane.
3.On the Options tab, select the Enabled DKIM Signing checkbox,click the Certificate tab.
4.In the Selector field, enter a unique name. (It is recommended the key is changed once every 12 months.) Adjust the Key Size accordingly, keeping in mind the larger the key, the stronger it is.Click Generate Key in the content pane toolbar.
5.The TXT Record Name and TXT Record Value fields will populate. Set up the TXT Record in DNS using this name and value.
If you don't know how to add TXT record to DNS,please click here
for the details.
Optional: On the DKIM Signing tab, adjust the settings regarding how closely the system should monitor messages in transit.