How do checkboxes work in Campaign Monitor?
Campaign Monitor does not have a checkbox/boolean data type. So we recommend mapping to either a Campaign Monitor text field or picklist.
A text field is the easiest when pushing data from Salesforce to Campaign Monitor as it is unrestricted. It will output either TRUE or FALSE.
You can also create a picklist (select once) field in Campaign Monitor, ensuring that you use TRUE or FALSE values.If you use our import wizard to map a Salesforce Checkbox to Campaign Monitor we can automatically create the field for you.