fix(tests): update tests and test helpers to current email/DNS APIs, use non-privileged ports, and improve robustness and resilience

readme.hints.md

@@ -1,5 +1,40 @@
 # Implementation Hints and Learnings
 
+## Test Fix: test.dcrouter.email.ts (2026-02-01)
+
+### Issue
+The test `DcRouter class - Custom email storage path` was failing with "domainConfigs is not iterable".
+
+### Root Cause
+The test was using outdated email config properties:
+- Used `domainRules: []` (non-existent property)
+- Used `defaultMode` (non-existent property)
+- Missing required `domains: []` property
+- Missing required `routes: []` property
+- Referenced `router.unifiedEmailServer` instead of `router.emailServer`
+
+### Fix
+Updated the test to use the correct `IUnifiedEmailServerOptions` interface properties:
+```typescript
+const emailConfig: IEmailConfig = {
+  ports: [2525],
+  hostname: 'mail.example.com',
+  domains: [], // Required: domain configurations
+  routes: []   // Required: email routing rules
+};
+```
+
+And fixed the property name:
+```typescript
+expect(router.emailServer).toBeTruthy();  // Not unifiedEmailServer
+```
+
+### Key Learning
+When using `IUnifiedEmailServerOptions` (aliased as `IEmailConfig` in some tests):
+- `domains: IEmailDomainConfig[]` is required (array of domain configs)
+- `routes: IEmailRoute[]` is required (email routing rules)
+- Access the email server via `dcRouter.emailServer` not `dcRouter.unifiedEmailServer`
+
 ## Network Metrics Implementation (2025-06-23)
 
 ### SmartProxy Metrics API Integration