{function formatted_subject message=[]}{strip}
    {if !empty($message.subject_formatted)}
        {$subject = $message.subject_formatted}
    {else}
        {$body = strip_tags($message.body)}
        {$subject = strip_tags($message.subject)|escape}
        {$subject = $subject|default:$body|default:'[`no subject`]'|truncate:50:'...':true}
    {/if}
    <span class="c-message-subject">{$subject}</span>
{/strip}{/function}