fix test

Author: icecrasher321

apps/sim/lib/messaging/email/validation.test.ts

@@ -10,6 +10,15 @@ vi.mock('@sim/logger', () => ({
   }),
 }))
 
+vi.mock('dns', () => ({
+  resolveMx: (
+    _domain: string,
+    callback: (err: Error | null, addresses: { exchange: string; priority: number }[]) => void
+  ) => {
+    callback(null, [{ exchange: 'mail.example.com', priority: 10 }])
+  },
+}))
+
 describe('Email Validation', () => {
   describe('validateEmail', () => {
     it.concurrent('should validate a correct email', async () => {