feat: support self-signed TLS via underscore domain convention
Domains starting with "_" (e.g. _chat.example.org) automatically use
self-signed TLS certificates instead of ACME/Let's Encrypt. The TLS
mode is derived from the domain name — no separate config option needed.
Internally, when config.tls_cert_mode is "self" (underscore domain):
- Generate self-signed certificates via openssl
- Set Postfix smtp_tls_security_level to "encrypt" (opportunistic TLS)
- Add smtp_tls_policy_map entry for underscore domains
- Skip ACME, MTA-STS and www CNAME checks in `cmdeploy dns`
- Serve /new via GET (not redirect to dcaccount:) with rate-limiting
(nginx limit_req, 2r/s burst=5)
- Return dclogin: URLs with ic=3 (AcceptInvalidCertificates) from /new
- Render QR codes client-side via JavaScript and qrcode-svg
- Use config.tls_cert_path/tls_key_path in Postfix, Dovecot and nginx
templates instead of hardcoded ACME paths
* docs: update index reference
* docs: adds control machine migration instructions
* docs: rename index ref
* docs: remove maddy-chatmail (404)
* docs: consistent underlining in header text
* docs: remove dedicated page reference
* docs: remove dedicated page for control machine migration
* docs: condense deployment machine migration into getting started per feedback
* docs: correct link to madmail
* docs: update verbiage based on feedback
refactor README.rst and architecture file into sphinx doc project, automatically deploying on main merges and PRs.
* add FAQs from https://chatmail.at/relays landing page
* fix links, and streamline postfix/dovecot mentioning
* add linkcheck to CI, fix several links and streamlihne DKIM section while at it
* some streamlining, rename to "overview"
* ci: upload documentation to chatmail.at/doc/relay
* ci: main should be uploaded when docs.yaml changes
* ci: fix typo
* Update .github/workflows/docs-preview.yaml
Co-authored-by: missytake <missytake@systemli.org>
