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.

Understanding Custom Fields

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

Default Fields

Every contact in Mailtrap has these default fields:

Email (Required)

Primary identifier for contacts

• Automatically created

• Cannot be deleted or modified

• Must be unique across your account

• Used for sending campaigns

Subscription Status

Creating Custom Fields

1

Navigate to Fields

Go to Contacts → Fields in your Mailtrap dashboard.

Contacts menu showing Fields tab

2

Click Create Field

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

Create Field button in the fields interface

3

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)

Form to create a new contact field with name, type, and merge tag inputs

Merge Tag Format Use underscores for multi-word merge tags (e.g., last_name, date_of_birth)

4

Save Your Field

Click Create to add the field to your account.

List of created contact fields including name and email

Field Types

Choose the appropriate field type based on your data:

Text

For short text values

• Names, titles, company names

• Short descriptions

• Single-line inputs

• Maximum 255 characters

Example: first_name, company, job_title

Number

Date

Boolean

List

Using Fields in Campaigns

Personalization with Merge Tags

Use merge tags to personalize your email content:

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>

Best Practices

Field Management 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

Common Use Cases

Field Limits and Considerations

Technical Specifications

• Maximum fields per account: Depends on your plan

• 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