Free tool
SPF, DKIM & DMARC Checker
Check whether a domain has valid SPF, DKIM and DMARC records set up, which is usually why business email lands in the spam folder.
Why this decides whether your email arrives
SPF lists which servers are allowed to send mail for your domain. DKIM signs each message so the receiver can prove it was not altered in transit. DMARC ties the two together and tells receiving servers what to do when a message fails, which is the only part that actually stops somebody forging mail in your name.
DKIM lives under a selector, which is a label chosen by whoever sends your mail. Google Workspace commonly uses google, Microsoft uses selector1, and cPanel servers usually use default. A missing result here means that selector is wrong, not necessarily that DKIM is absent.
A DMARC policy of none only collects reports and blocks nothing. It is the right place to start, but staying there for years means you have the paperwork without the protection. Moving to quarantine and then reject is the point of the exercise.