Generic OpenSRS Cluster B mail discovery Worker
IMAP/SMTP/POP host: mail.mailconfig.net
This Host: autodiscover.anderholdings.com  service=autodiscover  domain=anderholdings.com

Attach per zone (Cloudflare custom domains → this Worker):
  autoconfig.<domain>   → GET /mail/config-v1.1.xml
  autodiscover.<domain> → POST /autodiscover/autodiscover.xml
  mail.<domain>         → 301 https://mail.mailconfig.net/

DNS SRV (optional, per zone) targets mail.mailconfig.net / autodiscover.<domain>
Health: GET /health