posteo.de

Readiness by lane

Green: posteo.de. Thin bar: Webmail & Message Inboxes peer median.

Priority fixes for posteo.de

Ordered by impact and by how common each practice is among peers.

1. Priority 1 · Accelerate

   HTTP/2 negotiated

   Observed: The TLS handshake selected http/1.1 instead of HTTP/2.

   Why it matters: HTTP/2 sends many files over one connection, which speeds up pages with lots of images, styles and scripts.

   What to do: Enable HTTP/2 on your CDN or server. Most CDNs do this by default.

   72% of Webmail & Message Inboxes peers do this. Limit: Certificate and protocol were observed from one vantage point; CDNs can present different certificates by region.

   Guide: CDN Guide for Website Owners

2. Priority 2 · Harden

   DMARC policy enforces quarantine or reject

   Observed: The DMARC policy for posteo.de was p=none, which asks receivers to take no action on failing mail.

   What to do: Publish DMARC with p=none and a reporting address first, fix any legitimate senders that fail SPF or DKIM alignment, then move to quarantine and finally reject.

   58% of Webmail & Message Inboxes peers do this.

   Guide: A Practical Website Health Check for Owners

3. Priority 3 · Accelerate

   Modern image formats in use

   Observed: The homepage had 47 images and none used WebP or AVIF.

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

   41% of Webmail & Message Inboxes peers do this.

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

4. Priority 4 · Enable

   XML sitemap discoverable

   Observed: No sitemap was listed in robots.txt or found at /sitemap.xml.

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

   33% of Webmail & Message Inboxes peers do this.

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

What posteo.de already does well

Practices fewer than half of Webmail & Message Inboxes peers use.

• Nameservers spread across providersNameservers spread across more than one operator.19% of peers
• Reachable over IPv6IPv6 address published.27% of peers
• Static files cached for 30 days or moreLong-lived caching on static files.28% of peers

What we saw

Homepage checked

https://posteo.de/

Homepage response

HTTP 200, after 1 redirect

TLS

TLSv1.3, http/1.1

Certificate

DigiCert, 371-day validity, expiring 2027-02-24

DNS operators

8 self-run or other nameserver domains

HSTS

max-age 365 days, includeSubDomains, preload

DMARC policy

p=none

Homepage HTML

65 KB, gzip

Images on homepage

47 (png 45, svg 1, jpg 1)

Limits: homepage only, one location, one moment. Header checks reflect the homepage response; other pages may differ.

Stack and providers

Seen in the homepage response, certificate and DNS. Provider pages compare how their customers configure the same checks.

All 31 checks

Select a gap for the method and fix. How each check works

Compare with other Webmail & Message Inboxes sites

• att.net68
• emailondeck.com64
• laposte.net68
• libero.it67
• yopmail.com66

Webmail & Message Inboxes readiness benchmark