Add Job Categories to Job Alerts email template (https://wpjobmanager.com/document/overriding-add-template-files/)

content-email_job_listing.php

<?php
global $post;

$type     = get_the_job_type();
$location = get_the_job_location();
$company  = get_the_company_name();
// The arguments after 'job_listing_category' is "before" then "separator" then "after"
$job_categories = get_the_term_list( $post->ID, 'job_listing_category', '', ', ', '' );
echo "\n";

// Job type
if ( $type ) {
    echo esc_html( $type->name ) . ' - ';
}

// Job title
echo esc_html( $post->post_title ) . "\n";

// Location and company
if ( $location ) {
    printf( __( 'Location: %s', 'wp-job-manager-alerts' ) . "\n", esc_html( strip_tags( $location ) ) );
}
if ( $company ) {
    printf( __( 'Company: %s', 'wp-job-manager-alerts' ) . "\n", esc_html( strip_tags( $company ) ) );
}
if( $job_categories ){
	printf( __( 'Categories: %s', 'wp-job-manager-alerts' ) . "\n", esc_html( strip_tags( $job_categories ) ) );
}
// Permalink
printf( __( 'View Details: %s', 'wp-job-manager-alerts' ) . "\n", get_the_job_permalink() );