feat: Automatically detect rate limit from AWS with ability to override in .env

apps/api/.env.example

@@ -54,6 +54,12 @@ AWS_SES_SECRET_ACCESS_KEY=
 SES_CONFIGURATION_SET=plunk-configuration-set                     # Default: with open/click tracking
 SES_CONFIGURATION_SET_NO_TRACKING=plunk-configuration-set-no-tracking  # Optional: without tracking (enables toggle in UI)
 
+# Email sending rate limit (emails per second)
+# If not set, automatically fetches from AWS SES account quota (recommended)
+# Set this to override AWS quota (useful for setting lower limits or testing)
+# Default: Fetched from AWS (typically 14 for sandbox, higher for production accounts)
+# EMAIL_RATE_LIMIT_PER_SECOND=14
+
 # ==============================================================================
 # OAuth (Optional - for social login)
 # ==============================================================================

apps/api/src/app/constants.ts

@@ -45,6 +45,13 @@ export const AWS_SES_REGION = validateEnv('AWS_SES_REGION');
 export const AWS_SES_ACCESS_KEY_ID = validateEnv('AWS_SES_ACCESS_KEY_ID');
 export const AWS_SES_SECRET_ACCESS_KEY = validateEnv('AWS_SES_SECRET_ACCESS_KEY');
 
+// Email Processing Rate Limit (optional override)
+// If not set, will automatically fetch from AWS SES account quota
+// Set this to override AWS quota (useful for setting lower limits or testing)
+export const EMAIL_RATE_LIMIT_PER_SECOND = process.env.EMAIL_RATE_LIMIT_PER_SECOND
+  ? Number(process.env.EMAIL_RATE_LIMIT_PER_SECOND)
+  : undefined;
+
 // Storage
 export const REDIS_URL = validateEnv('REDIS_URL');
 export const DATABASE_URL = validateEnv('DATABASE_URL');

apps/api/src/jobs/email-processor.ts

@@ -11,10 +11,41 @@ import {EmailService} from '../services/EmailService.js';
 import {EventService} from '../services/EventService.js';
 import {MeterService} from '../services/MeterService.js';
 import {emailQueue, type SendEmailJobData} from '../services/QueueService.js';
-import {sendRawEmail} from '../services/SESService.js';
+import {getSendingQuota, sendRawEmail} from '../services/SESService.js';
-import {DASHBOARD_URI} from '../app/constants.js';
+import {DASHBOARD_URI, EMAIL_RATE_LIMIT_PER_SECOND} from '../app/constants.js';
 
-export function createEmailWorker() {
+/**
+ * Determine the email sending rate limit (emails per second)
+ * Priority: ENV variable > AWS SES quota > Safe default (14)
+ */
+async function getEmailRateLimit(): Promise<number> {
+  const DEFAULT_RATE_LIMIT = 14; // AWS SES sandbox limit - safe default
+
+  // If env variable is set, use it (override)
+  if (EMAIL_RATE_LIMIT_PER_SECOND !== undefined) {
+    console.log(`[EMAIL-PROCESSOR] Using rate limit from environment: ${EMAIL_RATE_LIMIT_PER_SECOND} emails/second`);
+    return EMAIL_RATE_LIMIT_PER_SECOND;
+  }
+
+  // Try to fetch from AWS SES
+  console.log('[EMAIL-PROCESSOR] Fetching rate limit from AWS SES...');
+  const quota = await getSendingQuota();
+
+  if (quota) {
+    console.log(
+      `[EMAIL-PROCESSOR] AWS SES quota: ${quota.maxSendRate} emails/second (${quota.sentLast24Hours}/${quota.max24HourSend} emails sent today)`,
+    );
+    return quota.maxSendRate;
+  }
+
+  // Fallback to safe default
+  console.warn(`[EMAIL-PROCESSOR] Failed to fetch AWS quota, using safe default: ${DEFAULT_RATE_LIMIT} emails/second`);
+  return DEFAULT_RATE_LIMIT;
+}
+
+export async function createEmailWorker() {
+  // Fetch the rate limit (from env, AWS, or default)
+  const rateLimit = await getEmailRateLimit();
   const worker = new Worker<SendEmailJobData>(
     emailQueue.name,
     async (job: Job<SendEmailJobData>) => {
@@ -157,7 +188,7 @@ export function createEmailWorker() {
       connection: emailQueue.opts.connection,
       concurrency: 10, // Process up to 10 emails concurrently
       limiter: {
-        max: 25, // Max 25 emails per second
+        max: rateLimit, // Max emails per second (from env, AWS SES quota, or default)
         duration: 1000,
       },
     },

apps/api/src/jobs/worker.ts

@@ -25,7 +25,7 @@ async function startWorkers() {
 
   try {
     // Start email worker
-    const emailWorker = createEmailWorker();
+    const emailWorker = await createEmailWorker();
     workers.push({name: 'email', worker: emailWorker});
     signale.success('[WORKER] Email worker started');
 

apps/api/src/services/SESService.ts

@@ -256,3 +256,26 @@ export const disableFeedbackForwarding = async (domain: string): Promise<void> =
     ForwardingEnabled: false,
   });
 };
+
+/**
+ * Get AWS SES account sending quota and rate limit
+ * @returns MaxSendRate (emails per second) or null if the call fails
+ */
+export const getSendingQuota = async (): Promise<{
+  maxSendRate: number;
+  max24HourSend: number;
+  sentLast24Hours: number;
+} | null> => {
+  try {
+    const quota = await ses.getSendQuota({});
+
+    return {
+      maxSendRate: quota.MaxSendRate ?? 14, // Default to sandbox limit if not provided
+      max24HourSend: quota.Max24HourSend ?? 200, // Default sandbox daily limit
+      sentLast24Hours: quota.SentLast24Hours ?? 0,
+    };
+  } catch (error) {
+    console.error('[SES] Failed to fetch sending quota:', error);
+    return null;
+  }
+};