feat: provision SMTP profiles from deployment receipts

docs/MAIL_HANDBOOK.md

@@ -43,6 +43,28 @@ session primitives, cryptographic secret helpers, audit infrastructure, and the
 module registry. Optional consumers provide narrow context through capabilities;
 Mail does not import their ORM or service implementations.
 
+## Deployment configuration packages
+
+Mail registers the `mail.configuration` capability for `smtp_profile`
+fragments. The provider reads the validated `mail.smtp` entry from the
+installer-generated infrastructure capability receipt. Receipt host and port
+are authoritative; the generic package workflow asks for missing non-secret
+transport fields such as security mode. An external relay may operate without
+authentication, or the operator may select an existing credential-envelope id.
+Inline usernames, passwords, tokens, and secret values are rejected.
+
+Tenant scope is the default. A system-scoped profile requires system settings
+or governance write authority. The fragment's stable slug is its idempotency
+identity: an absent profile is created, an exact profile is skipped, and a
+conflicting profile is preserved unless the reviewed fragment explicitly sets
+`on_conflict` to `update`. Credential bindings are added idempotently and are
+never removed merely because a package omits a credential reference.
+
+Preflight does not prove SMTP reachability. After apply, use the normal Mail
+profile test and Ops health surfaces. If the receipt says SMTP is unavailable,
+is invalid, or is not mounted, import is blocked with an operator-facing
+resolution instead of creating a partial profile.
+
 ## Interface patterns and unavailable actions
 
 Mail uses the platform's shared explorer, connection tree, adaptive form,