If you want to send or receive messages signed by root authorities and these authorities are not installed on the server, you must add a trusted root certificate manually.

Use the following steps to add or remove trusted root certificates to/from a server.

Mac OS X

FunctionMethod
AddUse command: sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain ~/new-root-certificate.crt
RemoveUse command: sudo security delete-certificate -c “<name of existing certificate>”

Windows

FunctionMethod
AddUse command: certutil -addstore -f “ROOT” new-root-certificate.crt
RemoveUse command: certutil -delstore “ROOT” serial-number-hex

Linux (Ubuntu, Debian)

FunctionMethod
AddCopy your CA to dir /usr/local/share/ca-certificates/ Use command: sudo cp foo.crt /usr/local/share/ca-certificates/foo.crt Update the CA store: sudo update-ca-certificates
RemoveRemove your CA. Update the CA store: sudo update-ca-certificates --fresh

Linux (CentOs 6)

FunctionMethod
AddInstall the ca-certificates package: yum install ca-certificates Enable the dynamic CA configuration feature: update-ca-trust force-enable Add it as a new file to /etc/pki/ca-trust/source/anchors/: cp foo.crt /etc/pki/ca-trust/source/anchors/ Use command: update-ca-trust extract

Linux (CentOs 5)

FunctionMethod
AddAppend your trusted certificate to file /etc/pki/tls/certs/ca-bundle.crt cat foo.crt >>/etc/pki/tls/certs/ca-bundle.crt