BIMI and VMC: is it worth it?
What BIMI shows in the inbox, the DMARC and logo requirements, VMC versus CMC certificates, the costs and a checklist for deciding whether to adopt it.
Guides
In-depth guides on email authentication, TLS, DNS and web security, plus a guide for every tool: what the check means, how to read the result and how to fix common problems.
In-depth guides
Blacklist removal playbook, list by list
What to do when your mail server IP or domain appears on a DNS blocklist: find the cause, fix it, request removal from each list and prevent relisting.
Content Security Policy without breaking your site
Build a CSP that stops injected scripts: report-only rollout, nonces and strict-dynamic, the directives that matter, and fixing violations step by step.
DKIM: selectors, key rotation and 2048-bit keys
How DKIM selectors work, how to publish 2048-bit keys that fit in DNS, and a rotation procedure that never breaks signatures on mail in transit.
How to read DMARC aggregate reports
What is inside a DMARC rua report, how to tell your own senders from forwarding and spoofing, and how to summarise the XML in your browser.
DMARC: from p=none to p=reject in 30 days
A week-by-week plan to move a domain from DMARC monitoring to full enforcement without blocking your own invoices, newsletters or support mail.
DNSSEC: should you turn it on, and how
What DNSSEC protects against, how the chain of trust works, which algorithms to choose, and a safe path to signing a zone without taking it offline.
Domain migration checklist: DNS, email, TLS and redirects
A step-by-step checklist for moving DNS providers, transferring registrars, switching mail hosts or renaming a domain without downtime or lost mail.
Email deliverability checklist (2026)
The DNS, authentication, infrastructure and list practices that decide whether your mail reaches the inbox, with a check for each item.
HSTS and the HSTS preload list
How Strict-Transport-Security works, how to raise max-age safely, what includeSubDomains can break, and the requirements and risks of preloading.
MTA-STS and TLS-RPT: step-by-step setup
Require encrypted delivery to your mail servers with MTA-STS (RFC 8461) and see TLS failures with TLS-RPT (RFC 8460), from testing mode to enforce.
The SPF 10-lookup limit: diagnosis and flattening
Why SPF fails with permerror after ten DNS lookups, how to count them including nested includes, and safer alternatives to flattening your record.
Subdomain takeover: detection and prevention
How dangling CNAME, NS and MX records let others serve content on your subdomains, how to find them in your own zones, and how to stop it happening.
TLS 1.3 migration and cipher selection
What changed in TLS 1.3, which protocol versions and cipher suites to allow in 2026, server configuration examples and how to test them.
Tool guides
31 guides
Guide list
Domain Health guide
What the XGM Domain Health check covers, how its A to F grades are calculated, and how to work through findings for email, DNS, TLS, headers and redirects.
DNS Lookup guide
How DNS resolution works, what each record type in the XGM DNS Lookup means, how to read the findings and how to troubleshoot common DNS problems.
WHOIS Lookup guide
How to read a WHOIS record with the XGM WHOIS Lookup: registrar, creation and expiry dates, EPP status codes, name servers and why some data is hidden.
Email Security guide
How SPF, DKIM, DMARC, MTA-STS, TLS-RPT and BIMI work, how to read every finding and the score in XGM Email Security, and how to fix common mistakes.
Subdomain takeover: detection and prevention
How dangling CNAME, NS and MX records let others serve content on your subdomains, how to find them in your own zones, and how to stop it happening.
Domain migration checklist: DNS, email, TLS and redirects
A step-by-step checklist for moving DNS providers, transferring registrars, switching mail hosts or renaming a domain without downtime or lost mail.
How to read DMARC aggregate reports
What is inside a DMARC rua report, how to tell your own senders from forwarding and spoofing, and how to summarise the XML in your browser.
MX & SMTP guide
How MX records route email, what XGM MX & SMTP checks in DNS and over SMTP for each mail server, from STARTTLS to open relay, and how to fix mistakes.
Blacklist Checker guide
How the XGM Blacklist Checker queries 77 DNS blocklists for an IP address or a domain and its mail servers, how to read the results and what to do next.
Email Header Analyzer guide
How to copy full email headers, what the XGM Email Header Analyzer shows about delivery hops, delays and authentication, and how to spot spoofing signs.
Record Builders guide
How to build SPF and DMARC records and write title, description, Open Graph and Twitter tags with XGM Record Builders, and what each warning means.
SSL Checker guide
What the XGM SSL Checker reads from a certificate and TLS connection, how to read the grade, chain, protocol and cipher findings, and how to fix them.
HTTP Headers Checker guide
What the XGM HTTP Headers Checker reports for HSTS, CSP, X-Frame-Options, Referrer-Policy and more, with ready-to-use fixes for nginx and other servers.
Redirect Checker guide
How the Redirect Checker follows HTTP, HTTPS and www variants to the final page, what 301, 302, 307 and 308 mean, and how to fix loops and long chains.
SEO Metadata Checker guide
What the SEO Metadata Checker reads from a home page, how to judge title and description length, canonical links and Open Graph tags, and how to fix them.
Request Inspector guide
How to read a User-Agent string with XGM Request Inspector, why the strings look so strange, how client hints change things and why UA sniffing is fragile.
Ping and Traceroute guide
How the XGM Ping and Traceroute tools test a public host from the XGM server, what latency, packet loss and hops mean, and why some hosts never reply.
IP Intelligence guide
What XGM IP Intelligence shows for an IP address or hostname: scope, reverse DNS, ASN, organisation and approximate location, and how reliable each is.
Port Scanner guide
How XGM Port Scanner tests TCP ports on a public host, what open, closed and filtered mean, which exposed ports are risky and how to close them.
JSON Formatter guide
How the XGM JSON Formatter validates JSON with the browser's strict parser, what common errors mean and how to fix trailing commas, quotes and more.
Code Formatter guide
What XGM Code Formatter removes and preserves when it minifies HTML, CSS and JavaScript or formats XML, and the whitespace cases that can change a layout.
Encoder / Decoder guide
What Base64, URL encoding and HTML entities are for, how XGM Encoder / Decoder converts UTF-8 text and number bases, and why encoding is never encryption.
URL & UTM guide
How XGM URL & UTM splits a URL into its parts and decoded query, builds UTM campaign links, and helps spot encoding problems and suspicious links.
Text Utilities guide
How XGM Text Utilities counts words, characters, lines and bytes, converts case and creates URL slugs, and why emoji and accents change the numbers.
JWT Decoder guide
How JSON Web Tokens are built, what the XGM JWT Decoder shows about claims and expiry, how signature verification works and which mistakes to avoid.
Regex Tester guide
How to test JavaScript regular expressions with the XGM Regex Tester: flags, groups, replacement syntax, and how to avoid slow patterns and mistakes.
Hash Generator guide
What cryptographic hashes and HMACs are, which algorithms the XGM Hash Generator computes, when MD5 and SHA-1 are still acceptable and when they are not.
Password Generator guide
How the XGM Password Generator creates random passwords in your browser, what entropy bits mean, which length to choose and how to store passwords safely.
UUID Generator guide
How the XGM UUID Generator creates UUID v4, UUID v7 and ULID identifiers, how they differ, which to use for database keys, and how to decode a UUID.
Timestamp Converter guide
How the XGM Timestamp Converter reads Unix seconds, milliseconds, ISO 8601 and RFC 2822 dates, converts time zones and avoids common date bugs.
Color Converter guide
How to convert colours between HEX, RGB, HSL and OKLCH with the XGM Color Converter, and how to check WCAG contrast ratios for readable text.