aggregates.yaml accepts a mail to a field of the record this one belongs to

The parser refused {notice.email} before the mailer could resolve it.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

src/aggregates/mod.rs

@@ -222,9 +222,10 @@ pub fn parse_aggregates_yaml(raw: &str) -> anyhow::Result<HashMap<String, Aggreg
                 if mail.subject.trim().is_empty() || mail.body.trim().is_empty() {
                     anyhow::bail!("aggregates.yaml: bucket {bucket:?}: state {state:?}: mail needs a subject and a body");
                 }
-                if !mail.to_submitter() && !(mail.to.contains('@') && !mail.to.contains(char::is_whitespace)) {
+                let through_a_record = crate::mail::parent_of(&mail.to).is_some();
+                if !mail.to_submitter() && !through_a_record && !(mail.to.contains('@') && !mail.to.contains(char::is_whitespace)) {
                     anyhow::bail!(
-                        "aggregates.yaml: bucket {bucket:?}: state {state:?}: mail.to must be `submitter` or one address, not {:?}",
+                        "aggregates.yaml: bucket {bucket:?}: state {state:?}: mail.to must be `submitter`, one address, or a field of the record this one belongs to like `{{notice.email}}`, not {:?}",
                         mail.to
                     );
                 }