1dd3aadb97
A mail.cnx.email CNAME (-> mx1.cnx.email) lets clients (Thunderbird etc.) use a friendly hostname for submission/IMAP. To avoid a TLS name mismatch the cert now carries mail.cnx.email as a SAN, so the acme_mx1 key is authorized to write _acme-challenge.mail too. The MX still points at mx1.cnx.email and --reuse-key keeps the DANE TLSA digest valid across the re-issue.