Fixing issue with mail content from SNS that is base64 encoded (#4576)

packages/local-mail-watcher/src/index.ts

@@ -7,6 +7,7 @@ import { SnsMessage } from './types/SNS'
 import { simpleParser } from 'mailparser'
 import axios from 'axios'
 import { convertToMailObject } from './lib/emailApi'
+import { decodeBase64 } from './lib/base64'
 
 console.log('Starting worker...')
 
@@ -91,13 +92,27 @@ app.post('/sns', async (req, res) => {
     const message = JSON.parse(snsMessage.Message) as {
       notificationType: string
       content: string
+      receipt?: {
+        action?: {
+          encoding?: string
+        }
+      }
     }
     if (message.notificationType != 'Received') {
       console.log('Not an email, failing...')
       res.status(400).send()
+      return
     }
 
-    const mailContent = await simpleParser(message.content)
+    // Check if content is base64 encoded and decode if necessary
+    let emailContent = message.content
+    if (message.receipt?.action?.encoding === "BASE64") {
+      console.log("Detected BASE64 encoded content, decoding...")
+      emailContent = decodeBase64(message.content)
+      console.log("Processed BASE64 content")
+    }
+
+    const mailContent = await simpleParser(emailContent)
     const mail = convertToMailObject(mailContent)
     console.log(mail)
     await (
@@ -108,7 +123,7 @@ app.post('/sns', async (req, res) => {
       delay: 500,
     })
     res.sendStatus(200)
-
+    
     res.status(200).send()
     return
   }

packages/local-mail-watcher/src/lib/base64.js

@@ -0,0 +1,19 @@
+/**
+ * Utility functions for handling base64 encoding/decoding
+ */
+
+/**
+ * Decodes a base64 string to UTF-8 text
+ * Uses Node.js Buffer but with type safety
+ */
+export function decodeBase64(base64String: string): string {
+    try {
+      // Use a type-safe approach without relying on global
+      // @ts-ignore - Ignore TypeScript error for Buffer
+      return Buffer.from(base64String, 'base64').toString('utf-8');
+    } catch (error) {
+      console.error('Error decoding base64 string:', error);
+      return base64String; // Return original string if decoding fails
+    }
+  }
+