Shortcodes for custom fields use the following syntax.

{{ subscriber.field_identifier }}

If your field identifier is “first_name” then the correct shortcode, to insert the subscribers first name into an email, would be:

{{ subscriber.first_name }}

If the field identifier was “name” then the correct shortcode would be:

{{ subscriber.name }}

If you want to use a default value, you can use the following syntax:

Hi {{ subscriber.first_name | default: “there” }}

This would produce “Hi John” if the name John was given for the first name field; otherwise, it would output “Hi there”.

These options can also be used for more control.

{% if subscriber.first_name %}
Hi {{ subscriber.first_name }},
{% else %}
Hi there,
{% endif %}

Or

{% unless subscriber.first_name == null %}
Hi {{ subscriber.first_name }},
{% else %}
Hi there,
{% endunless %}

Shortcodes and conditionals can be used in email subject lines.