1. First, you need to get a digital certificate from a Certification Authority (CA). The certificate proves the identity of the sender of the email.
1. After obtaining the digital certificate, import it into the browser that you’ll use to access Zimbra Desktop or Zimbra Web Client.
1. Open Zimbra and go to the “Preferences” tab.
1. On the left side, select “Mail”.
1. Scroll down to “Signatures” and create the signature you want to use.
1. Under the option “Security”, select the digital certificate you have installed.
1. Select “Digitally Sign Mail”.
1. Click “Save” to finish signing the email.
Note: This sequence might be slightly different depending on the version of Zimbra you are using, but it should give you a general direction to follow.
