diff --git a/crates/common/src/config/smtp/queue.rs b/crates/common/src/config/smtp/queue.rs
index 60499d76..6764084c 100644
--- a/crates/common/src/config/smtp/queue.rs
+++ b/crates/common/src/config/smtp/queue.rs
@@ -390,10 +390,12 @@ fn parse_queue_throttle(config: &mut Config) -> QueueThrottle {
         host: Vec::new(),
         outbound_concurrency: config
             .property_or_default::<usize>("queue.threads.remote", "25")
-            .unwrap_or(25),
+            .unwrap_or(25)
+            .max(1),
         local_concurrency: config
             .property_or_default::<usize>("queue.threads.local", "10")
-            .unwrap_or(10),
+            .unwrap_or(10)
+            .max(1),
     };
 
     let all_throttles = parse_throttle(
diff --git a/crates/store/src/backend/s3/mod.rs b/crates/store/src/backend/s3/mod.rs
index df07ba4e..76bd9ac9 100644
--- a/crates/store/src/backend/s3/mod.rs
+++ b/crates/store/src/backend/s3/mod.rs
@@ -100,7 +100,7 @@ impl S3Store {
                 500..=599 if retries_left > 0 => {
                     // wait backoff
                     tokio::time::sleep(Duration::from_secs(
-                        1 << (self.max_retries - retries_left).max(6),
+                        1 << (self.max_retries - retries_left).min(6),
                     ))
                     .await;
 
@@ -130,7 +130,7 @@ impl S3Store {
                 500..=599 if retries_left > 0 => {
                     // wait backoff
                     tokio::time::sleep(Duration::from_secs(
-                        1 << (self.max_retries - retries_left).max(6),
+                        1 << (self.max_retries - retries_left).min(6),
                     ))
                     .await;
 
@@ -161,7 +161,7 @@ impl S3Store {
                 500..=599 if retries_left > 0 => {
                     // wait backoff
                     tokio::time::sleep(Duration::from_secs(
-                        1 << (self.max_retries - retries_left).max(6),
+                        1 << (self.max_retries - retries_left).min(6),
                     ))
                     .await;