Attach files from WPForms file upload field directly to an email

attach-files-from-wpforms.php

add_filter( 'wpforms_emails_send_email_data', 'wpf_prepare_files', 10, 2 );

/**
 * Prepare file attachment.
 * 
 * @param  Array $data      Email Data.
 * @param  Obj   $email_obj Email Object.
 * 
 * @return Obj The Email Data with attachment.
 */
function wpf_prepare_files( $data, $email_obj ) {

	$entry = $email_obj->fields;
	$files = array();

	foreach( $entry as $field ) {
		if ( 'file-upload' !== $field['type'] || empty( $field['value'] ) ) {
			continue;
		}

		$files[] = ABSPATH . wp_make_link_relative( $field['value'] );
	}

	$data['attachments'] = $files;

	return $data;
}