diff --git a/.env.self-host.example b/.env.self-host.example
index 90a2df3..b9db920 100644
--- a/.env.self-host.example
+++ b/.env.self-host.example
@@ -145,6 +145,21 @@ SMTP_DOMAIN=smtp.example.com
 # Default: true
 # AUTO_PROJECT_DISABLE=false
 
+# ========================================
+# OPTIONAL: Self-Hosting User Management
+# ========================================
+# Controls whether new user signups are allowed
+# When enabled (true), the signup endpoint will reject new user registration attempts
+# Useful for private instances or when you want to manually manage users
+# Default: false
+# DISABLE_SIGNUPS=false
+
+# Controls whether email validation checks are performed on signup
+# When enabled (true), validates emails for disposable domains, plus-addressing, domain existence, and MX records
+# When disabled (false), skips these validation checks and allows any email format
+# Default: false
+# VERIFY_EMAIL_ON_SIGNUP=false
+
 # ========================================
 # ADVANCED (rarely needed)
 # ========================================
diff --git a/CLAUDE.md b/CLAUDE.md
index 65b9299..5bdfdda 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -64,9 +64,9 @@ to run them separately (e.g., for debugging), use `dev:server` and `dev:worker`
 ### Applications (`apps/`)
 
 - **api**: Express.js API server with TypeScript (ESM), uses @overnightjs/core
-    - HTTP API endpoints for the platform
-    - Background cron jobs (workflow processor, domain verification)
-    - **Worker process** (separate): BullMQ worker for processing email, campaign, and workflow queues
+  - HTTP API endpoints for the platform
+  - Background cron jobs (workflow processor, domain verification)
+  - **Worker process** (separate): BullMQ worker for processing email, campaign, and workflow queues
 - **web**: Next.js app (Pages Router) - Main platform (next-app.useplunk.com)
 - **landing**: Next.js app (Pages Router) - Marketing site (next.useplunk.com)
 - **wiki**: Next.js app - Documentation site (next-wiki.useplunk.com)
@@ -148,6 +148,12 @@ Required for builds and deployment (see turbo.json and .env.example):
 - Notifications (optional): `NTFY_URL` (ntfy.sh topic URL or self-hosted server for system notifications)
 - Platform Email Notifications (optional): `PLUNK_API_KEY` (enables email notifications to users for critical events like
   project disabled, billing limits, etc. If not set, only ntfy notifications are sent)
+- Self-hosting User Management (optional):
+  - `DISABLE_SIGNUPS` (default: false) - When set to true, prevents new user signups via the API
+  - `VERIFY_EMAIL_ON_SIGNUP` (default: false) - When set to true, validates emails on signup for disposable domains,
+    plus-addressing, domain existence, and MX records
+- Security (optional): `AUTO_PROJECT_DISABLE` (default: true) - Controls whether projects are automatically disabled when
+  bounce/complaint rate thresholds are exceeded
 
 **Important Notes:**
 
@@ -159,7 +165,8 @@ Required for builds and deployment (see turbo.json and .env.example):
   client-side access
 
 ## Plugins
+
 There are two plugins installed for you to use.
 
 - frontend-design: This plugin can help you to create polished user interfaces. Use it when working on design-related tasks.
-- superpowers: This plugin can help you with advanced tasks such as refactorings, new features or architectural changes. Use it when you need extra assistance beyond basic coding.
\ No newline at end of file
+- superpowers: This plugin can help you with advanced tasks such as refactorings, new features or architectural changes. Use it when you need extra assistance beyond basic coding.
diff --git a/apps/api/src/app/constants.ts b/apps/api/src/app/constants.ts
index 2d8c872..06c5b2f 100644
--- a/apps/api/src/app/constants.ts
+++ b/apps/api/src/app/constants.ts
@@ -104,6 +104,12 @@ export const PLUNK_ENABLED = PLUNK_API_KEY !== '' && PLUNK_FROM_ADDRESS !== '';
 // Useful for self-hosters who want to manage project status manually
 export const AUTO_PROJECT_DISABLE = validateEnv('AUTO_PROJECT_DISABLE', 'true') === 'true';
 
+// Self-hosting Configuration (optional)
+// Controls whether new user signups are allowed (default: false)
+export const DISABLE_SIGNUPS = process.env.DISABLE_SIGNUPS === 'true';
+// Controls whether email validation checks are performed on signup (default: false)
+export const VERIFY_EMAIL_ON_SIGNUP = process.env.VERIFY_EMAIL_ON_SIGNUP === 'true';
+
 // Email Verification & Password Reset
 export const TOKEN_EXPIRY_SECONDS = 3600; // 1 hour
 export const EMAIL_VERIFICATION_RATE_LIMIT = 3; // Max 3 emails per hour
diff --git a/apps/api/src/controllers/Auth.ts b/apps/api/src/controllers/Auth.ts
index 2acf986..c6b7b66 100644
--- a/apps/api/src/controllers/Auth.ts
+++ b/apps/api/src/controllers/Auth.ts
@@ -7,6 +7,7 @@ import * as React from 'react';
 
 import {
   DASHBOARD_URI,
+  DISABLE_SIGNUPS,
   EMAIL_VERIFICATION_RATE_LIMIT,
   EMAIL_VERIFICATION_RATE_WINDOW,
   GITHUB_OAUTH_ENABLED,
@@ -15,6 +16,7 @@ import {
   PASSWORD_RESET_RATE_LIMIT,
   PLUNK_ENABLED,
   TOKEN_EXPIRY_SECONDS,
+  VERIFY_EMAIL_ON_SIGNUP,
 } from '../app/constants.js';
 import {prisma} from '../database/prisma.js';
 import {redis, REDIS_ONE_MINUTE} from '../database/redis.js';
@@ -63,33 +65,43 @@ export class Auth {
   @Post('signup')
   @CatchAsync
   public async signup(req: Request, res: Response, _next: NextFunction) {
-    const {email, password} = AuthenticationSchemas.login.parse(req.body);
-
-    // Verify email is valid and not disposable/plus-addressed
-    const verification = await EmailVerificationService.verifyEmail(email);
-
-    if (
-      verification.isDisposable ||
-      verification.isPlusAddressed ||
-      !verification.domainExists ||
-      !verification.hasMxRecords
-    ) {
-      // Build list of reasons for notification
-      const reasons: string[] = [];
-      if (verification.isDisposable) reasons.push('disposable email');
-      if (verification.isPlusAddressed) reasons.push('plus addressing');
-      if (!verification.domainExists) reasons.push('domain does not exist');
-      if (!verification.hasMxRecords) reasons.push('no MX records');
-
-      // Send notification about failed signup attempt
-      await NtfyService.notifyFailedSignupAttempt(email, reasons);
-
+    // Check if signups are disabled
+    if (DISABLE_SIGNUPS) {
       return res.json({
         success: false,
-        data: 'This email address cannot be used for signup',
+        data: 'New user signups are currently disabled',
       });
     }
 
+    const {email, password} = AuthenticationSchemas.login.parse(req.body);
+
+    // Verify email is valid and not disposable/plus-addressed (if verification enabled)
+    if (VERIFY_EMAIL_ON_SIGNUP) {
+      const verification = await EmailVerificationService.verifyEmail(email);
+
+      if (
+        verification.isDisposable ||
+        verification.isPlusAddressed ||
+        !verification.domainExists ||
+        !verification.hasMxRecords
+      ) {
+        // Build list of reasons for notification
+        const reasons: string[] = [];
+        if (verification.isDisposable) reasons.push('disposable email');
+        if (verification.isPlusAddressed) reasons.push('plus addressing');
+        if (!verification.domainExists) reasons.push('domain does not exist');
+        if (!verification.hasMxRecords) reasons.push('no MX records');
+
+        // Send notification about failed signup attempt
+        await NtfyService.notifyFailedSignupAttempt(email, reasons);
+
+        return res.json({
+          success: false,
+          data: 'This email address cannot be used for signup',
+        });
+      }
+    }
+
     const user = await UserService.email(email);
 
     if (user) {
diff --git a/apps/api/src/controllers/Oauth/Github.ts b/apps/api/src/controllers/Oauth/Github.ts
index a25bbb0..74f4406 100644
--- a/apps/api/src/controllers/Oauth/Github.ts
+++ b/apps/api/src/controllers/Oauth/Github.ts
@@ -4,11 +4,13 @@ import type {NextFunction, Request, Response} from 'express';
 import {
   API_URI,
   DASHBOARD_URI,
+  DISABLE_SIGNUPS,
   GITHUB_OAUTH_CLIENT,
   GITHUB_OAUTH_ENABLED,
   GITHUB_OAUTH_SECRET,
 } from '../../app/constants.js';
 import {prisma} from '../../database/prisma.js';
+import {BadRequest} from '../../exceptions/index.js';
 import {jwt} from '../../middleware/auth.js';
 import {NtfyService} from '../../services/NtfyService.js';
 import {UserService} from '../../services/UserService.js';
@@ -81,6 +83,11 @@ export class Github {
     let isNewUser = false;
 
     if (!user) {
+      // Check if signups are disabled
+      if (DISABLE_SIGNUPS) {
+        throw new BadRequest('New user signups are currently disabled');
+      }
+
       user = await prisma.user.create({
         data: {
           email,
diff --git a/apps/api/src/controllers/Oauth/Google.ts b/apps/api/src/controllers/Oauth/Google.ts
index 5c2a3ce..7c070f6 100644
--- a/apps/api/src/controllers/Oauth/Google.ts
+++ b/apps/api/src/controllers/Oauth/Google.ts
@@ -4,11 +4,13 @@ import type {NextFunction, Request, Response} from 'express';
 import {
   API_URI,
   DASHBOARD_URI,
+  DISABLE_SIGNUPS,
   GOOGLE_OAUTH_CLIENT,
   GOOGLE_OAUTH_ENABLED,
   GOOGLE_OAUTH_SECRET,
 } from '../../app/constants.js';
 import {prisma} from '../../database/prisma.js';
+import {BadRequest} from '../../exceptions/index.js';
 import {jwt} from '../../middleware/auth.js';
 import {NtfyService} from '../../services/NtfyService.js';
 import {UserService} from '../../services/UserService.js';
@@ -71,6 +73,11 @@ export class Google {
     let isNewUser = false;
 
     if (!user) {
+      // Check if signups are disabled
+      if (DISABLE_SIGNUPS) {
+        throw new BadRequest('New user signups are currently disabled');
+      }
+
       user = await prisma.user.create({
         data: {
           email,