DKIM signature is supported by Hosted Email Security for all outgoing messages from a particular domain. The email messages from the domain can be verified by the recipients to ensure that they are legitimate and that the administrator of the domain has not altered any of the messages or attachments in transit.
Here's how to enable SPF for Zimbra if you use it to send emails to your clients.
Follow these steps to enable DKIM signing for TrendMicro HES:
To make DKIM signing available for the chosen domain:
Adding a DKIM record to DNS:
To prevent your domains from spoofing, enable DMARC. Register for a DMARC trial right away!