---
title: "Updating Contacts with an External Identifier"
slug: "update-contacts-with-external-identifier"
updated: 2025-10-02T09:49:28Z
published: 2025-10-02T09:49:28Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Updating Contacts with an External Identifier

## Goal

Update contact profiles in Mapp Engage by importing a file where contacts are matched and updated based on their external identifier.

---

## Background Information

The external identifier stores an additional ID on the contact profile in Mapp Engage. It can contain letters and numbers, and it often originates from an external CRM. When used for imports, you can update a contact’s address without deleting data or creating a duplicate profile.

- In CSV files, the external identifier uses the header `user.identifier`.
- In XML files, it appears in the `identifier` element.

### Limitations

- Matching during import is always done on the external identifier.
- Using only external identifiers during import does not create new users. Creating a new user requires at least one standard identifier, such as an email address or mobile number, alongside the unique `user.identifier`.
- If you import an external identifier and a contact address, and the address differs from the one stored in Mapp Engage, the system overwrites the existing address with the address from your file. The external identifier remains unchanged.
- For external identifiers to serve as the primary means of identification, each contact should have a unique ID. Mapp Engage does not validate uniqueness, so duplicates are technically possible but strongly discouraged.

---

## Prerequisites

- A correctly formatted CSV or XML import file. See: [CSV Format for Contact Imports](/v1/docs/csv-format-for-contact-imports) and [XML Format for Contact Imports](/v1/docs/xml-format-for-contact-imports).
- The file includes the external contact ID:
  - CSV header: `user.identifier`
  - XML element: `identifier` Optionally, include a contact address such as an email address or mobile number.

---

## Procedure

### Option A: Importing Manually

1. Go to *Audience > Group Management > Groups*.
2. From the context menu next to the target group, select **Members**.
3. Click **Import**.
4. Expand **Advanced Options**.
5. Select **Use External Identifier**.
6. Complete the remaining import settings and start the import.

---

### Option B: Importing with an Automation

1. In the main navigation, go to *Automation > Time-based*.
2. Click **New Automation**.
3. Enter a name for the automation.
4. From **Job**, select **Import Contacts**.
5. Enter the import details.
6. Click **Additional Parameters**. Two input fields appear.
7. In the first field, enter `source-use-customeridentifier`. In the second field, enter `true`. These values are case-sensitive.
8. Click **Schedule** to define the date and time. See *Schedule Time-Based Automation (window)*.
9. Click **Save & Activate**. The automation runs at the scheduled times.

---

## Example

An import file contains the following data:

| user.identifier | user.email |
| --- | --- |
| 12345 | user@example.com |

- In Mapp Engage, a contact with an external identifier `12345`already exists, but their email address is different.
- After the import, the system updates the contact’s profile and replaces the old email address with `user@example.com`.
- The external identifier `12345` remains unchanged.

## Related

- [Importing Contacts](/import-contacts.md)