Use this when the user asks whether mail from a domain will reach Gmail or Outlook, or why it is rejected or goes to spam, such as "will Gmail accept mail from example.com sent from 203.0.113.7?". Pass the domain, the sending IPv4 address if known, the return-path domain (mail_from) if known and, optionally, up to 5 DKIM selectors. Returns one verdict (likely_accepted, at_risk, likely_rejected or incomplete) with a verdict per provider, the top 3 causes each with one fix, the exact SPF and DMARC records to paste (records_to_paste) and the DKIM steps for the detected mail provider (fix_steps), every rule checked with its official source link (SPF for the IP, DKIM, DMARC, reverse DNS, blocklists), the 6 blocklists with their terms links, what was not checked, and the source and as_of date. Gmail and Outlook are always both reported, so there is no provider argument. It reads public DNS and free blocklists only: it sends no test message and cannot see sender reputation, so it does not promise inbox placement.