Guides: email security and discoverability

Plain-language explanations of the DNS records that decide whether your domain can be spoofed, and of the files, tags and crawler rules that decide whether search and AI engines can find and quote your site, each with examples and the fixes AstraVerify recommends.

• What is SPF? Sender Policy Framework explained

  SPF is a DNS TXT record listing the servers allowed to send email for your domain. Learn the syntax, -all vs ~all, the 10-lookup limit and common SPF mistakes.

• What is DKIM? DomainKeys Identified Mail explained

  DKIM signs outgoing email and publishes the public key in DNS under a selector. Learn how it works, what a selector is and why 2048-bit keys matter.

• What is DMARC? Policies, alignment and reports explained

  DMARC tells receivers what to do when mail fails SPF and DKIM alignment and reports who sends as your domain. Learn none, quarantine, reject and rollout.

• What are MX records? How email routing works

  MX records tell the world which servers accept email for your domain. Learn how priority works, what a null MX is and the mistakes that break delivery.

• How the AstraVerify email security score works

  AstraVerify scores a domain out of 100: MX 25, SPF 25, DKIM 20, DMARC 30. Learn what earns points, why a score is capped while a fix is open and how to reach 100.

• robots.txt for search and AI crawlers: what to allow

  How robots.txt controls Googlebot, Bingbot, GPTBot, ClaudeBot and PerplexityBot, why the Sitemap line must be absolute, and the wildcard mistakes to avoid.

• How to make your site readable by ChatGPT, Perplexity and Claude

  Why AI answer engines cannot cite a site they cannot fetch: CDN bot blocks, challenge pages and robots rules, and how to allow OAI-SearchBot and PerplexityBot.

• What is llms.txt? A plain-text summary for AI agents

  llms.txt is a plain-text file at your site root that tells language models what the site is, who it is for and where the main pages are. Format and example.

• JSON-LD structured data for small business sites

  The three JSON-LD blocks every small business or SaaS site needs (Organization, WebSite, a page type), with copy-ready examples and the mistakes to avoid.

• www vs apex: pick one host and redirect the other

  Why serving your site on both www and the bare domain splits ranking signals, how to choose a canonical host, and the redirect and canonical-tag rules that fix it.

• How the Discoverability score is calculated

  The five parts of the Discoverability score: crawl access, plumbing, metadata, structured data, answer-engine readiness. Why blocking AI crawlers costs points.

• The AstraVerify seal: how to add it to your website

  A small badge telling visitors mail from your domain is authenticated (SPF, DKIM, DMARC enforced), verified live. One line of HTML for any site or CMS.

• Gmail and Yahoo sender requirements: check your domain

  Gmail, Yahoo and Outlook sender rules in one table: SPF, DKIM, DMARC, alignment, one-click unsubscribe, spam rate. Which ones a domain check covers, and the fixes.

• Is my site blocking GPTBot, ClaudeBot or PerplexityBot? A two-minute check

  Three checks that show whether AI crawlers can read your site: what each bot token does, how to read robots.txt for them, and fetching a page as GPTBot or ClaudeBot.

• Check your llms.txt: what a valid file needs

  Six checks for an llms.txt file: location, status, content type, structure, the one-sentence definition and the links. What the scan tests and how to fix each one.

• AstraVerify vs MXToolbox, dmarcian and EasyDMARC: how to choose

  Four tools that read the same DNS records for different jobs: when a one-page domain check is enough, when you need a DMARC report platform, where MXToolbox fits.

• Core Web Vitals for a small business site: what to fix first

  LCP, CLS and INP explained through the five causes behind most small-site scores, each with a one-line fix, and what fixing our own site took: CLS 0.11 to 0.

• SPF ~all vs -all: what the difference is and how to move safely

  What ~all (softfail) and -all (fail) tell receivers, why ~all is the most common SPF finding on business domains, and three steps to reach -all without losing mail.

• 47-day TLS certificates: the dates, and what actually breaks

  TLS certificate lifetimes drop to 100 days in 2027 and 47 in 2029, and domain validation reuse drops to 10. What changes, what breaks first, and what to check now.