WP Mail SMTP has a built-in Domain Checker. It automatically scans your domain's DNS records for rules called DMARC, SPF, and DKIM and will warn you if they are missing.
If you're using Google Workspace or a custom domain with Gmail, we recommend adding these to your DNS. Jump down to our table of common Gmail errors for instructions.
Free Gmail users (without a custom domain) can ignore these warnings. As a free Gmail user, you don't have control over the sending domain's DNS, so you can't add these records.