DKIM is essential to set a clear boundary between legitimate emails sent from your own domain and ones sent via spoofing and impersonation. DKIM along with DMARC can help you prevent phishing and spoofing attacks and protect your domain in the long run.
Unfortunately, BigCommerce doesn’t natively support DKIM signing, currently. However, BigCommerce allows you to route your emails through a system that has DKIM enabled for it, allowing your emails to be signed with DKIM keys. For further information on how you can do that, please contact the BigCommerce support team.
Learn how to enable SPF for BigCommerce.