Sync Contacts with 'Lightning Sync'

Allow Users to sync using Lightning Sync by creating a Lightning Sync configuration:

Classic: Setup | Administer | Outlook Integration and Sync | Settings | Expand "Let users sync Contacts, Events or both between Microsoft Exchange and Salesforce " | under Define Sync Settings, click "New Config" button 
Lightning: Click the gear icon and go to Setup | Email | Outlook Integration and Sync |  Expand "Let users sync Contacts, Events or both between Microsoft Exchange and Salesforce " | under Define Sync Settings, click "New Config" button  

After users are added to an Exchange Sync configuration and the configuration is made active, Exchange Sync will create a Salesforce_Sync folder as a subdirectory under the Contacts directory in each of the user’s email accounts in Exchange. If this folder is not created the folder can be created manually by the user if needed.

Users who are syncing contacts from Exchange to Salesforce or syncing both ways may choose which Exchange contacts sync into Salesforce by moving the contacts into the Salesforce_Sync folder. The first sync for users may not be in real time and could take several hours to ensure maximum performance for all users.

Note: Lightning Sync only allows a maximum limit of 50,000 Contacts to sync.