Fix Rate limiter panics when periods under 1 second are used

CHANGELOG.md

@@ -17,6 +17,7 @@ If you are upgrading from v0.16.x, replace the binary (or run `docker pull`). If
   - Disabled aliases continue receiving messages.
 - JMAP for File Storage: `FileNode/get` returns a stale state string.
 - Make `SieveSystemInterpreter.defaultReturnPath` and `MtaQueueQuota.match` optional expressions.
+- Rate limiter panics when periods under 1 second are used.
 
 ## [0.16.7] - 2026-05-28
 

crates/store/src/dispatch/lookup.rs

@@ -301,8 +301,9 @@ impl InMemoryStore {
         soft_check: bool,
     ) -> trc::Result<Option<u64>> {
         let now = now();
-        let range_start = now / rate.period.as_secs();
-        let range_end = (range_start * rate.period.as_secs()) + rate.period.as_secs();
+        let period = rate.period.as_secs().max(1);
+        let range_start = now / period;
+        let range_end = (range_start * period) + period;
         let expires_in = range_end - now;
 
         let mut bucket = Vec::with_capacity(key.len() + U64_LEN + 1);