The Mail application found on Mac OS X systems supports the transmission and decoding of encrypted email that uses public key unfrastructure (PKI) certificates. You will see an open padlock icon on messages that will be sent unencrypted. If you have a public certificate for a recipient, you can click on the button with that symbol on it to encrypt the message.
OS X also provides the command line
security utility for managing
certificates. You can use
security find-certificate email_address
where email_address is the email address to which you wish to
send email to determine if you already have a public certificate for the
recipient in your keychain.
If you are using PKI software from Entrust on the system, you can also use it to retrieve public certificates for recipients.
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