Can I use the Salesforce Contact or Lead Id?
By default a Salesforce record is linked to Campaign Monitor via the standard email address field found on the contact or lead object. You can override this behaviour when you add records to Campaign Monitor u our import wizard
1. Make sure your source - report, list, SOQL contains a Salesforce Contact or Lead ID.
2. Via the import wizard map the Salesforce Contact or Lead ID to the Salesforce ID field on the mapping screen.
3. When the import wizard runs a subscriber list membership record will be created in Salesforce. This will be linked to a contact or lead based on the ID rather than the email address.