Experts, email marketers, and documentation all suggest that small senders *should* use a dedicated sending domain. This is primarily because it's crucial for building and controlling sender reputation, improving deliverability, and enhancing brand recognition. Setting up SPF, DKIM, and DMARC records is vital for domain authentication. Unlike dedicated IPs, senders are never 'too small' for a dedicated domain. Furthermore, utilizing tools like Google Postmaster Tools is highly recommended for monitoring domain health. Finally, it's easy to setup and doesn't cost anything.