Once Yoxel Mailbox Assistant add-in is installed you should see it in the Outlook ribbon:
Click the ribbon button to start Yoxel add-in in the task pane.
The very first time around the add-in will ask you to authorize access to your Office 365 and your Salesforce accounts.
1. Getting offline access to your Office 365 account allows the add-in to send emails when you're not online.
You'll see details of the requested permissions. Click 'Accept' to confirm.
2. Getting access to your Salesforce account is essential to activating the rest of the add-in functionality:
You'll see details of the requested permissions. Click 'Allow' to confirm.
3. After you've completed the two authorization steps your add-in should be active and should show its "snapshot" page to you. At that point please switch to the 'Settings' tab to verify that you've connected proper Salesforce account. This is the page where you can de-activate the add-in or re-connect a different Salesforce account.