# Uploading Contacts in Bulk
### Steps
You can add contacts in bulk using a .csv file. To add contacts in bulk into the Marketing Engine, perform the following steps:
1. Click *Segments*.
2. Click *Contacts*.
3. Under Add New Contacts, click *Upload File*.
4. In the "Upload Your File" section, you can upload a .csv file from your system. The file must include all contact details, with the email ID being a mandatory field.
{% hint style="info" %}
**Note:** To ensure a successful upload, we recommend downloading the sample .csv file and following its format when uploading your contacts in bulk.
{% endhint %}
5. You'll see a preview of your file's contents. If everything looks correct, click *Next.*
6. **Map File**
In the *Map File* section, map the columns from your file to the corresponding contact attributes shown on the screen where you want to add the data.
{% hint style="danger" %}
Proper mapping allows Marketing Engine to segment your contacts later in the **Audience** section based on these attributes. If any column isn’t mapped automatically, you can select the correct attribute from the drop-down menu. If the required attribute doesn’t exist, you have the option to create a custom attribute to capture additional contact details.
For more information, refer to the section [**Creating Custom Objects & Custom Fields for Data Management**](https://docs.satisfilabs.com/resource-center/marketing-engine/segments/create-custom-object-and-custom-fields-for-contact-data-management)**.**
If your file contains headers that match Marketing Engine's contact attributes, they will be mapped automatically.
Be sure to map the **email ID** field, as it is mandatory.
{% endhint %}
7. **Update SMS/WhatsApp Consent**
Before sending WhatsApp or SMS messages to your uploaded contacts, you must obtain explicit opt-in consent from them. WhatsApp notifications require prior consent, and in many countries, SMS marketing also requires customer consent.
To apply consent to your contacts, click **Update SMS/WhatsApp Consent.** You can choose to grant consent for either WhatsApp, SMS, or both. Consent can be applied to:
* **All contacts**, or
* **Specific contacts** by mapping the appropriate column in your uploaded file to the SMS and WhatsApp consent fields.
8. **Review & Confirm**
In this step, review and confirm the contact details before uploading.
* Selecting **"Overwrite existing contact details"** will update duplicate contacts with the data from your .csv file.
* Enabling **"Import empty fields to erase existing contact details"** will replace any existing information with blank fields from your .csv file.
* You also have the option to **blacklist** the imported email contacts.
Finally, ensure that your contacts have opted in to receive email marketing from you by checking the box under the **Opt-In Agreement.**
9. Click Ok.
10. In the *Add to List Section,* you can either add contacts to an existing list or create a new one. To add them to an existing list, simply select it from the options. If you prefer to create a new list, click **"Create a New List,"** enter a name, and save your contacts to it.
11. You can assign tags to your uploaded list for better organization and segmentation.
12. Click *Save*.
Once you click *Done*, you can see the import history, which provides details like the number of contacts in your file, the number of contacts successfully added, the number of invalid contacts, the status of the uploaded file, and more.
You also have an option to download the error report, if any, to see the issue with the invalid contacts.
