Hi have some new contact data I will be importing as part of a campaign. Some of the names in this data already exist as contacts within Zoho, and many don't. In the data, I have a column/field for 'source' which I will give a value denoting this campaign (let's say, June 2024). 

Is there a way I can run this import so that it will not update existing data in Zoho? For example, if there is a contact in my CRM with the source May 2024, and they are also in this import, I need their 'source' field to remain May 2024 instead of being updated June 2024.

Any ideas? I know salesforce has a basic 'Do not overwrite existing data' checkbox which achieves this.