What does the retrospective sync button do?

A 'Retrospective Sync' will push the mapped data from Salesforce to Campaign Monitor for all Leads/Contacts currently associated with this Subscriber List. Please note:

• It only pushes data from Salesforce to Campaign Monitor (not Campaign Monitor to Salesforce)
• It will apply to all records related to the subscriber list
• If this sync is not run, then the new mappings will only apply to Salesforce Leads/Contacts that are subsequently updated or created