Bulk update contacts. A maximum of 250 contacts can be updated in a single request.

Each item in the request body array must identify a contact and provide the data to be updated. A contact can be identified in three ways, with the following priority:

1. By its internal id.
2. By its contactCode and channelType.
3. By its externalCode.

If externalCode is used as an identifier, multiple contacts might be updated simultaneously.