Import upstream v0.16.25, stripped

Upstream commit: 3f657330c0f49a015a3a372fb59669b5cccbca6d
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 118 in 50 files
Dangling module declarations removed: 5
Edits turning enterprise off: 25
Third-party code: 14 files, 0 not in THIRD-PARTY.md
Renamed identifiers: 67 in 19 files
Verification: clean

The same Enterprise footprint as v0.16.24. The build check is clean
apart from the expected errors in the rebuilt-feature tests. A
bug-fix release: DKIM rotation, IMAP failed-login answers, DNSBL
multi-code scoring and negative TTLs, Pyzor on short messages, queue
quotas with an empty match, RocksDB info-log rotation, and
Autodiscover schema handling.

CHANGELOG.md

@@ -2,6 +2,33 @@
 
 All notable changes to this project will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.16.25] - 2026-10-05
+
+If you are upgrading from v0.16.x, replace the binary (or run `docker pull`). If you are upgrading from v0.15.x and below, please read the [upgrading documentation](https://github.com/stalwartlabs/stalwart/blob/main/UPGRADING/v0_16.md) for more information on how to upgrade from previous versions.
+
+## Added
+
+## Changed
+
+## Fixed
+- JMAP: Creating a `MaskedEmail` with `emailDomain` fails with `forbidden` for every domain when the account has addresses on more than one domain.
+- Autodiscover: Requests for a response schema other than Outlook's, such as ActiveSync (`mobilesync`), are answered with the Outlook settings instead of error 601.
+- IMAP:
+  - `LOGIN` and `AUTHENTICATE` with a wrong, expired or unknown app password or API key are answered with an untagged `NO`, so clients keep waiting for the command to complete until the connection times out.
+  - The failed login that exceeds the maximum number of authentication failures is answered with an untagged `NO` before the connection is closed.
+- DKIM:
+  - A rotation moves the active key to retiring even when its successor fails to publish or propagate, so outgoing mail is sent unsigned until a retry publishes the new key. The DNS write failure is also not logged and the task reports success.
+  - Keys created while DNS management was manual, or before DKIM was added to the published records, are never rotated after DNS management becomes automatic. Domains already affected start rotating once a `DkimManagement` task is created for them.
+  - After switching DNS management from automatic to manual, a due rotation activates a new key that was never published in DNS, so signatures fail verification, and retiring the old key is retried forever.
+- Spam filter:
+  - Messages with no text line long enough for a Pyzor digest are checked with the digest of empty input and tagged `PYZOR`.
+  - DNSBL answers with several return codes, such as a Spamhaus ZEN listing in both SBL and PBL, are scored for only the first code returned.
+  - DNSBL lookups that return "not listed" are cached for 24 hours regardless of the zone's negative TTL.
+  - Removing a duplicate training sample of a message reclassified on the same day clears the blob link of the sample that is kept.
+- MTA: Queue quotas with an empty `match` expression are never enforced, including the global queue quota created on first start.
+- RocksDB: The info log (`LOG`, `LOG.old.*`) grows without limit because log rotation and retention are left at RocksDB defaults.
+- WebUI: A blob store read error at startup, such as an S3 authentication failure, stops the web interface from being downloaded.
+
 ## [0.16.24] - 2026-09-27
 
 If you are upgrading from v0.16.x, replace the binary (or run `docker pull`). If you are upgrading from v0.15.x and below, please read the [upgrading documentation](https://github.com/stalwartlabs/stalwart/blob/main/UPGRADING/v0_16.md) for more information on how to upgrade from previous versions.