Email authentication guides

Practical, sourced guides for small businesses on SPF, DKIM, DMARC and the Gmail and Yahoo sender rules.

• Google and Yahoo bulk-sender rules: what small businesses need to do
  Plain-English guide to the Gmail and Yahoo sender requirements: SPF, DKIM, DMARC, one-click unsubscribe and spam-rate limits, and what applies to small senders.
• DMARC basics: none, quarantine, reject and a staged rollout
  What DMARC does, what p=none, p=quarantine and p=reject mean, how alignment works, and how to move to enforcement safely in stages.
• How to check your SPF, DKIM and DMARC records
  Step-by-step: look up SPF, DKIM and DMARC with dig or nslookup, read the results, and spot common errors like multiple SPF records or too many lookups.