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Category benchmark · Snapshot 23 October 2026

Webmail & Message Inboxes: website readiness

31 configuration checks across 33 Webmail & Message Inboxes sites from the SID website catalog, with 20 individual profiles for sites in the Chrome UX Report top 50K.

Sites measured
33

all popularity bands

Median readiness index
64/100

all sites: 64

Profiles
20

top-50K sites

Weakest lane
Recover

lowest weighted score

Readiness by lane

Enable

60/100

All sites 77

Harden

67/100

All sites 56

Accelerate

54/100

All sites 64

Recover

19/100

All sites 10

Biggest gaps for Webmail & Message Inboxes sites

The checks with the most room to improve, weighted by impact.

  1. Static files cached for 30 days or more

    28% observed · all sites 51%

    Give versioned (fingerprinted) CSS, JavaScript, fonts and images Cache-Control: public, max-age=31536000, immutable, and change the file name whenever the content changes.

    Guide: Browser Caching Guide for Website Owners

  2. Modern image formats in use

    41% observed · all sites 40%

    Serve WebP or AVIF with a JPEG or PNG fallback, either through an image CDN or by generating both formats at build time.

    Guide: AVIF, WebP, JPEG, and PNG: Choose the Right Image Format

  3. No render-blocking scripts in <head>

    30% observed · all sites 48%

    Add defer to scripts that need the DOM, async to independent ones such as analytics, or move them to the end of the body.

    Guide: Control Third-Party Scripts Before They Control Your Page

  4. HTTP/3 advertised

    15% observed · all sites 37%

    Turn on HTTP/3 at your CDN. Browsers fall back to HTTP/2 automatically, so the risk is low.

    Guide: CDN Guide for Website Owners

  5. XML sitemap discoverable

    33% observed · all sites 70%

    Generate an XML sitemap of canonical URLs, reference it in robots.txt and submit it in Google Search Console.

    Guide: XML Sitemap Guide: Include Only URLs You Stand Behind

  6. security.txt published

    20% observed · all sites 7.1%

    Publish /.well-known/security.txt with at least Contact and Expires fields, as RFC 9116 requires, and review it before it expires.

    Guide: A Practical Website Health Check for Owners

Where Webmail & Message Inboxes sites lead

  • DNSSEC signed39% observedall sites 8%
  • HSTS kept for at least a year61% observedall sites 34%
  • Framing restricted76% observedall sites 51%
  • CAA records limit who can issue certificates33% observedall sites 13%

Stack mix

CDN and edge

Platform or framework

DNS operator

Certificate authority

Readiness leaders

Webmail & Message Inboxes sites in the top 50K with the highest share of observed practices (at least 26 of 31 checks measured). This lists only what we observed on 23 October 2026; owners can request a correction.

  1. tempmail.ninja83/100
  2. gmx.net77/100
  3. gmx.at77/100
  4. mail.com77/100
  5. web.de71/100
  6. generator.email70/100
  7. privateemail.com70/100
  8. att.net68/100
  9. laposte.net68/100
  10. libero.it67/100

All 31 checks for Webmail & Message Inboxes

CheckLaneObservedAll sitesMeasured
HTTP requests move to HTTPSHarden93%91%29
HSTS kept for at least a yearHarden61%34%33
TLS 1.3 negotiatedHarden91%91%32
Certificate has more than 14 days leftHarden100%99%32
Certificate lifetime of 100 days or lessHarden38%67%32
CAA records limit who can issue certificatesHarden33%13%33
DNSSEC signedHarden39%8%33
security.txt publishedHarden20%7.1%30
DMARC policy enforces quarantine or rejectHarden58%39%33
X-Content-Type-Options: nosniffHarden64%48%33
Framing restrictedHarden76%51%33
Content Security Policy presentHarden42%32%33
Referrer-Policy setHarden42%24%33
HTTP/2 negotiatedAccelerate72%90%32
HTTP/3 advertisedAccelerate15%37%33
HTML compressedAccelerate88%93%33
Static files cached for 30 days or moreAccelerate28%51%25
Modern image formats in useAccelerate41%40%22
Offscreen images lazy-loadedAccelerate78%62%18
No render-blocking scripts in <head>Accelerate30%48%33
robots.txt publishedEnable58%76%31
XML sitemap discoverableEnable33%70%30
Reachable over IPv6Enable27%48%33
Canonical URL declaredEnable52%68%33
Meta description writtenEnable82%84%33
Mobile viewport configuredEnable88%94%33
Structured data presentEnable24%51%33
Social preview image setEnable36%57%33
Page language declaredEnable76%90%33
At most one redirect to the homepageEnable85%98%33
Nameservers spread across providersRecover19%10%32

Webmail & Message Inboxes profiles

Readiness index shown next to each site.