# Custom Fields

Custom fields allow you to store additional information about your contacts beyond their email address. Use these fields to personalize campaigns and create targeted segments.

{% hint style="info" %}
**What are Custom Fields?** Custom fields are variables that store specific information about your contacts, such as:

* Personal details (first name, last name, birthday)
* Geographic information (city, country, timezone)
* Preferences (product interests, communication frequency)
* Custom data specific to your business
  {% endhint %}

## Default Fields

Every contact in Mailtrap has these default fields:

{% tabs %}
{% tab title="Email (Required)" %}
**Primary identifier for contacts**

* Automatically created
* Cannot be deleted or modified
* Must be unique across your account
* Used for sending campaigns
  {% endtab %}

{% tab title="Subscription Status" %}
**Tracks consent and engagement**

* Subscribed
* Unsubscribed
* Pending (awaiting confirmation)
  {% endtab %}
  {% endtabs %}

## Creating Custom Fields

{% stepper %}
{% step %}
**Navigate to Fields**

Go to **Contacts** → **Fields** in your Mailtrap dashboard.

<div align="left" data-with-frame="true"><img src="/files/FbRx2js41iCmk3pcilYo" alt="Contacts menu showing Fields tab" width="375"></div>
{% endstep %}

{% step %}
**Click Create Field**

Select the **Create Field** button to open the field creation form.

<div align="left" data-with-frame="true"><img src="/files/apsgrEHXLvzBHOsdMMz0" alt="Create Field button in the fields interface" width="563"></div>
{% endstep %}

{% step %}
**Configure Field Properties**

Fill in the field details:

* **Field Name**: Display name (e.g., "First Name")
* **Type**: Select the appropriate data type
* **Merge Tag**: Variable for personalization (e.g., `first_name`)

<div align="left" data-with-frame="true"><img src="/files/cQTEpn6ykIRLyE5FkNs7" alt="Form to create a new contact field with name, type, and merge tag inputs" width="563"></div>

{% hint style="warning" %}
**Merge Tag Format** Use underscores for multi-word merge tags (e.g., `last_name`, `date_of_birth`)
{% endhint %}
{% endstep %}

{% step %}
**Save Your Field**

Click **Create** to add the field to your account.

<div align="left" data-with-frame="true"><img src="/files/1fE7wsHjcyrqiz5A9jGS" alt="List of created contact fields including name and email" width="563"></div>
{% endstep %}
{% endstepper %}

## Field types

Choose the appropriate field type based on your data:

{% tabs %}
{% tab title="Text" %}
**For short text values**

* Names, titles, company names
* Short descriptions
* Single-line inputs
* Maximum 255 characters

Example: `first_name`, `company`, `job_title`
{% endtab %}

{% tab title="Number" %}
**For numeric values**

* Age, scores, counts
* Integers and decimals
* Mathematical operations in segments

Example: `age`, `purchase_count`, `loyalty_points`
{% endtab %}

{% tab title="Date" %}
**For date and time values**

* Birthdays, anniversaries
* Registration dates
* Last activity timestamps
* Format: YYYY-MM-DD

Example: `birthday`, `registration_date`, `last_purchase`
{% endtab %}

{% tab title="Boolean" %}
**For yes/no values**

* Preferences and flags
* Subscription statuses
* Feature toggles
* Values: true/false

Example: `is_vip`, `newsletter_subscriber`, `has_purchased`
{% endtab %}

{% tab title="List" %}
**For predefined options**

* Categories, segments
* Multiple choice values
* Dropdown selections

Example: `product_interest`, `customer_tier`, `preferred_language`
{% endtab %}
{% endtabs %}

## Using Fields in Campaigns

### Personalization with Merge Tags

Use merge tags to personalize your email content:

{% code title="Example Email Template" %}

````

</div>

### Dynamic Content

Create conditional content based on field values:

<div data-gb-custom-block data-tag="code" data-title='Conditional Content Example'>
```liquid

<div data-gb-custom-block data-tag="if" data-expression='preferred_language == "Spanish"'>

  Hola {{first_name}},

<div data-gb-custom-block data-tag="elsif" data-0='French' data-1='French' data-2='French'></div>

  Bonjour {{first_name}},

<div data-gb-custom-block data-tag="else"></div>

  Hello {{first_name}},

</div>

````

{% endcode %}

## Best practices

{% hint style="success" %}
**Field fanagement tips:**

1. **Plan before creating**: Map out all fields you need before importing contacts
2. **Use descriptive names**: Make field names clear and intuitive
3. **Consistent naming**: Use a naming convention for merge tags
4. **Data validation**: Choose appropriate field types to ensure data quality
5. **Document usage**: Keep notes on what each field represents
   {% endhint %}

## Technical limitations

* **Field name length**: Up to 50 characters
* **Merge tag length**: Up to 50 characters
* **Text field value**: Up to 255 characters
* Cannot delete fields with existing data
* Each account can have up to 40 Fields.


---

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