You can upload Base64-encoded certificates in either privacy-enhanced email (PEM) or public key cryptography standard #12 (PKCS #12) format from your management computer to the FortiMail unit.

Importing a certificate may be useful when:

If you generated the certificate request using the FortiMail unit, after you submit the certificate request to CA, the CA will verify the information and register the contact information in a digital certificate that contains a serial number, an expiration date, and the public key of the CA. The CA will then sign the certificate and return it to you for installation on the FortiMail unit. To install the certificate, you must import it. For other related steps, see “Obtaining and installing a local certificate”.

If the FortiMail unit’s local certificate is signed by an intermediate CA rather than a root CA, before clients will trust the FortiMail unit’s local certificate, you must demonstrate a link with trusted root CAs, thereby proving that the FortiMail unit’s certificate is genuine. You can demonstrate this chain of trust either by:

To include a signing chain, before importing the local certificate to the FortiMail unit, first open the FortiMail unit’s local certificate file in a plain text editor, append the certificate of each intermediate CA in order from the intermediate CA who signed the FortiMail unit’s certificate to the intermediate CA whose certificate was signed directly by a trusted root CA, then save the certificate. For example, a local certificate which includes a signing chain might use the following structure: