update

ts/mail/delivery/classes.delivery.queue.ts

@@ -613,6 +613,12 @@ export class UnifiedDeliveryQueue extends EventEmitter {
     // Stop processing
     this.stopProcessing();
     
+    // Clear the check timer to prevent memory leaks
+    if (this.checkTimer) {
+      clearInterval(this.checkTimer);
+      this.checkTimer = undefined;
+    }
+    
     // If using disk storage, make sure all items are persisted
     if (this.options.storageType === 'disk') {
       const pendingWrites: Promise<void>[] = [];