When should you map the 'Contact ID' while overwriting records using the import function?
Since the 'Contact ID' is a system field, you cannot overwrite any of those values. When you overwrite records using the import function, the system will identify all matching records using email for Leads/Contacts, Name for Accounts and more.
If you have two or more accounts with the same name, the system will only overwrite the first matching account. The 'Contact ID' will help you identify the records which match exactly. Each record is assigned a unique ID (for example, Contact ID for Contacts or Lead ID for Leads), and this unique ID will be visible in the list of exported data from Zoho CRM. So if you are trying to import the exported data, you can map the Contact ID field to make sure that they are overwritten properly.
In Zoho CRM, each record is assigned with a unique ID. When you import contacts, the system identifies all the existing contacts either using the Contact ID or email address (if the Contact ID has not been mapped). The Contact ID is generated by Zoho CRM, and is available when you export all contacts. However, if your file contains a different Contact ID to the one generated by Zoho CRM, the system will not update any contacts.