What happens when I change an email address in Campaign Monitor?

Changing an email address in Campaign Monitor can have significant implications, as email addresses function as unique identifiers within the platform. However, there is no flag in Campaign Monitor to show that an email address has changed, so from an API perspective, we are unaware of the update.

It is worth noting that if you change the standard email field in Salesforce, we will update the corresponding subscriber Campaign Monitor. 

If you or a client changes the Campaign Monitor email address, when the sync next runs it will detect a new subscriber. This will create a new subscriber list membership record in Salesforce. As the email address will differ from the one stored in Salesforce, the record will not be linked to the contact or lead.