After installing the Unipass Mailock Outlook add-in you will be asked to sign in the first time you read or send a secure email within each session.
Click on the Sign in with Unipass Identity option to login using your Unipass certificate or Unipass Login Credentials (username and passphrase).
Remember though, although it's possible for anyone to download and install the Outlook Add-in, only Business Premium users are able to use it to read and send messages using Unipass Mailock. If you'd like to find out about upgrading, you can read more here.