Some user attributes (custom fields) are reserved by system because their value is automatically updated when certain events occur.
| emUnsubDate | Last email unsubscribe date |
| numberOfPurchases | Total number of purchases |
| createdOn | User creation date |
| isCustomer | Is customer |
| lastPurchaseDate | Date of the last purchase |
| isSpam | Flagged as spam? |
| isHardBounced | Flagged as hard bounced |
| isSubscribed | Is subscribed to newsletter |
| isSubscribedAlerts | Is subscribed to transactional emails |
| totalPurchasesValue | Total value of purchases |
| source | Acquisition source |
| lastEmailClickDate | Date of last clicked email |
| lastPurchaseValue | Total value of last purchase |
| lastEmailOpenDate | Date of last opened email |
| lastVisitDate | Date of last visit to the site |
| score | Score value |
| emSubDate | First email subscribe date |