Salesforce Whitelisting
Truly uses the Oauth mechanism to modify records in Salesforce on behalf of a given user - as a result, this mechanism must be enabled under the Salesforce Admin Panel (this is almost always enabled by default)
IT Whitelisting
Some organizations protect their email data more heavily than other kinds (contacts, calendar, etc). In this case, they implement a 'whitelist' policy that requires IT to put Truly on a trusted list of vendors before data can be accessed.
Google Apps
Sign into your Google Apps Admin account >> Navigate to Security Tab >> API Controls Option
Click Manage Third Party App Access
Click Configure New App >> Oauth App Name or Client ID
Enter the string “535350133202-5c6ost43877e6gntuvbvod99m4gbdtfd.apps.googleusercontent.com” and hit search >> Select the Truly App.
Have your Account Manager enable email sync as a feature for your tenant.
Have each user navigate into their Truly app >> Settings Tab >> Integrations >> Complete the Gmail integration.
Office365
Log into the Azure portal
Navigate to the Azure Active Directory App
Click on App Registrations >> All Applications >> Truly (Application/Client Id: 31842c8e-1a32-43a3-a87c-0e486170fcd6)
Click on Grant Admin Consent for all users.
NOTE: this does not give Truly access to all user's data. It simply whitelists users in your org to individually grant access to Truly via Oauth 2.0 authentication/enrollment.