You'll find your secure messages, sent using the Gateway Outlook Add-in, in your Sent Items, just like your other emails. When you open a sent message you'll see a Mailock button, at the top right which tells you if the message was sent securely or not:
For messages sent securely, clicking on the button gives you an option to 'View access details'. This shows if/when a message has been opened, if any attachments have been opened, how many failed attempts of meeting the message security there were and gives you the option to revoke/block access to the message.
Before you can view this detail, the add-in guides you through an automated verification step:
Click on 'Ok' to start the verification. An email is sent to your inbox, which the add-in looks for and automatically completes the verification:
Once complete, you'll see the message access details:
You can click in the 'Revoked' box to revoke a message to stop recipients from opening it, if, for example, it had been sent in error:
Revoke works per recipient so you'll need to tick the boxes next to each recipient if you want to fully block access to a message.
If the box is already ticked, you can click it to unrevoke (allow access to) the message.