The video above is a quick tutorial on how to sign into Cirrus Insight using a custom Salesforce sandbox domain. The demonstration is done from within an Outlook environment.

Step By Step Guide: 

1. Open Outlook and click the home menu to make sure we can then select Cirrus Insight from within the Outlook toolbar.
2. Click the Cirrus Insight button to launch the sidebar application.
3. Enter your email address tied to your Cirrus Insight user account, and click sign in.
4. Underneath the Sign In with the Salesforce button, click the drop-down caret and enter a custom sandbox URL - which will ask for your sandbox domain.
   1. To get a hold of your domain, you'll need to go back into your Salesforce sandbox environment.
   2. Within your sandbox dashboard, click the avatar button to view your profile info.
   3. Copy the URL displayed underneath your name NOT the URL displayed within the browser - it won't work for authentication purposes.
   4. Copy the domain from Setup > My Domain or your Salesforce profile. Don't paste the address from your browser bar. URLs ending in lightning.force.com or my.salesforce-setup.com are not login domains and will cause the connection to fail or loop.
   5. Don't use your production domain for a sandbox connection. This causes a "grant type not supported" error.
5. Back in Outlook, submit the copied domain into the input field. Click the green check button and sign in with Salesforce.
   1. You may be prompted to login via a pop-up window
6. Once everything is approved, you will be taken into the Cirrus Insight application while connected to your sandbox environment. 
7. Allow the permission sets, and then you are fully connected and can test out the different services that you wish!

Gmail

1. In Gmail, open the Cirrus Insight sidebar.
2. Sign out, then enter your email address and click sign in.
3. Underneath the Sign In with Salesforce button, click the drop-down caret and choose the custom sandbox URL option.
4. Paste your domain into the input field.
5. Click the green check button, then sign in with Salesforce.

Sidebar vs. sync

This sets your sidebar connection only. If you also use automated sync, repeat the custom-domain connection in the Dashboard under My Profile > Connections. See Connect sync services to a sandbox.