Some of what you see here is sample content. While the community forms, part of the members, reviews, ratings and discussions are seeded examples. Every one is badged Sample, and they do count towards the totals on this site. Vendor pages, the security data and the tools are real.
SPF and DMARC record builder
Build the DNS records, understand what each tag actually does, and get them in an order that will not bounce your own invoices. Most domains that fail here fail because somebody published p=reject on a Friday.
Everything you type stays in this tab. Share copies a link, never your inputs, unless the tool says it encodes them in the URL.
SPF
Ctrl-click to select several. Each include costs one of your ten DNS lookups.
DMARC
SPF has a hard limit of ten DNS lookups. Exceed it and the check returns permerror, which most receivers treat as a failure, so a domain can break by adding one more vendor.