Import upstream v0.16.24, stripped

Upstream commit: af37a234981722493b74623a983581691d2b70b6
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: 62 in 18 files
Verification: clean

The same Enterprise footprint as v0.16.23. The build check fails only on
tests/src/directory/issuer.rs, unchanged since v0.16.23: it calls a helper
from upstream's Enterprise-only OIDC test, and tests issuer-based directory
routing, an Enterprise feature. main has never carried it.

crates/smtp/src/inbound/data.rs

@@ -694,7 +694,12 @@ impl<T: SessionStream> Session<T> {
                         .map(|a| a.as_str())
                         .unwrap_or_default(),
                 )
-                .with_message(parsed_message);
+                .with_message(
+                    edited_message
+                        .as_deref()
+                        .and_then(|message| MessageParser::new().parse(message))
+                        .unwrap_or(parsed_message),
+                );
 
             let modifications = match self.run_script(script_id, script.clone(), params).await {
                 ScriptResult::Accept { modifications } => modifications,

crates/smtp/src/inbound/hooks/message.rs

@@ -132,7 +132,7 @@ impl<T: SessionStream> Session<T> {
                                 name: "X-Quarantine".into(),
                                 value: "true".into(),
                             });
-                            FilterResponse::accept()
+                            continue;
                         }
                     };