Adding Custom Fields to Your Optin Form

Adding extra custom fields to WordPress optin form

By default, only name and email address fields are present when you create an optin form in MailOptin. Follow the guide below to learn how to add extra fields such as a phone number or company name.

Adding Custom Fields to Form

Firstly, create a new optin form or modify an existing one. Open the Form Builder by clicking the optin name or Edit link.

Open the Fields section, click the “Add Custom Field” button.

Adding extra custom fields to WordPress optin form

Fill out the form to define the custom field by supplying the title, the type of field (such as text, text area, checkbox, radio button, select dropdown, date picker, hidden field), color, background color and font family. You also have the option to mark the field as required.

You can add as many fields as you want and sort the fields via drag-and-drop to re-arrange them.

Must Read: How to Let Users Select Email List in Your WordPress Form

Map Custom Fields To Your Email Service Provider / CRM

What happens to the data collected by the custom fields? I am sure you will want to pass or save the data to your email marketing software or CRM. Follow the guide below to learn how to map the extra fields you added to the form to the custom fields in your ESP/CRM.

Using MailChimp for this demonstration, the list subscribers will be added to in MailChimp has Address and Phone number fields beside the regular first name, last name and email fields.

Firstly, we need to add a phone and address field to the form as described in the first section above.

Open the Integrations panel in the customizer, Select MailChimp as the email provider and the list subscribers will be added to.

MailChimp integration for optin form

Click the Map Custom Fields button to reveal a UI where we can map the custom or extra fields added to the form to their corresponding fields in the selected MailChimp list. Don’t forget to click the little “Save” button when you are done.

Besides the form fields, you can also map and save the referral URL, IP address, conversion page and optin campaign name against a custom field.

Mapping custom fields in MailOptin

Easy right?

So when visitors signup to your list, the information they entered to the custom field will be included in their profile in MailChimp.

MailChimp subscriber profile with custom field

Integrations That Work Differently

Not all email marketing and CRM integrations we support works exactly as MailChimp described above. Let’s go over the integrations and their differences.


Klaviyo has a number of fields besides the name and email address that they specially recognise called “special identify properties”. They include Phone Number, Organization, Job Title, City, State, Country etc.

In the field mapping UI in MailOptin, you can only map custom fields added to your form to these special properties.

Custom field mapping to Klaviyo special properties

Other custom fields not mapped will not be neglected but saved against the subscriber profile as custom properties.

Klaviyo subscriber profile with custom field


You don’t have to do any field mapping for Sendlane integration because MailOptin automatically saves the custom field data submitted by a subscriber against their profile in Sendlane.

Sendlane subscriber profile with custom field


Similar to Sendlane, you can’t use the map custom fields UI for Sendy integration. However, you can save custom field data against a subscriber by ensuring the title of the custom fields added to your optin form matches the Personalization tag of the corresponding field in Sendy.

Say you have a Company Name field with personalization tag CompanyName, ensure the title of the custom field is CompanyName.

Sendy custom field UI listing

If you have any question, please let us know.