mta-sts.toppymicros.com

MTA-STS policy hosting repo for toppymicros.com.

This repository is intended to be published via GitHub Pages on the domain mta-sts.toppymicros.com and serve the policy file at:

• https://mta-sts.toppymicros.com/.well-known/mta-sts.txt

GitHub Pages setup

• GitHub Pages: serve from the default branch (commonly main) at the repository root
• Custom domain: mta-sts.toppymicros.com (see CNAME)
• HTTPS must be enabled

Customize for your domain

If you reuse this repo for your company (e.g., your company website is hosted on GitHub Pages), swap toppymicros.com to your domain everywhere:

• Update CNAME to mta-sts.<your-domain>
• Update the policy URL to https://mta-sts.<your-domain>/.well-known/mta-sts.txt
• Update .well-known/mta-sts.txt:
  • Set mx: lines to match your domain’s actual MX hosts (check with dig MX <your-domain>)
  • Choose mode: testing first, then move to enforce
• Create the DNS TXT record at _mta-sts.<your-domain> with v=STSv1; id=<some-id>

Served policy

Path: https://mta-sts.toppymicros.com/.well-known/mta-sts.txt

version: STSv1
mode: testing
mx: mail.protonmail.ch
mx: mailsec.protonmail.ch
max_age: 86400

DNS TXT record

Create a TXT record:

• Name/Host: _mta-sts.toppymicros.com (or _mta-sts if your DNS provider appends the zone)
• Type: TXT
• Value:

v=STSv1; id=20260106T000000Z

After publishing, verify:

dig TXT _mta-sts.toppymicros.com +short

Also verify the policy is reachable over HTTPS:

curl -i https://mta-sts.toppymicros.com/.well-known/mta-sts.txt

Notes

• mode: testing is a safe rollout; switch to enforce once confident.
• max_age is 1 day; increase (e.g., 604800) after validating delivery.
• Update id when the policy changes to force re-fetching by senders.

Customize for your domain

If you want to reuse this repo for your company domain, replace toppymicros.com with your domain and update:

• CNAME to mta-sts.<your-domain>
• .well-known/mta-sts.txt mx: lines to match dig MX <your-domain>
• DNS TXT _mta-sts.<your-domain> to v=STSv1; id=<some-id> (bump id whenever the policy changes)

Work log

• Added .well-known/mta-sts.txt with Proton Mail MX hosts, mode: testing, and max_age: 86400.
• Added .nojekyll so GitHub Pages serves the .well-known path.
• Documented the required TXT at _mta-sts.toppymicros.com and policy details above.

License

MIT: see LICENSE.