--- title: "Test sign-up and login emails in Replit apps · Proxy Mail QA" description: "Building with Replit Agent? Find out whether your app's login sends email, then check its codes and links reach the published app, with a private inbox." url: https://proxymail.qa/built-with/replit --- 1. [Home](https://proxymail.qa/) 2. [AI app builders](https://proxymail.qa/built-with) # Testing sign-up and login emails in apps built on Replit Replit Agent can build, run and publish a full app with accounts. Which emails your users get depends on the login it set up: Replit Auth, Clerk Auth, or your own. Here's how to tell, and how to check each one before you share your app. Updated 15 October 2026 ## Which login does your app use? Open the **Auth** pane in your workspace, or ask the Agent: “Which authentication does this app use?” | Login | Who sends the emails | Test with Proxy Mail QA | | -------------------------------------------------------------------------------- | ------------------------------------------------------------------------ | ------------------------------------------- | | **Replit Auth:** people sign in with a Replit account | Replit, for Replit accounts. Your app sends none to sign in | Only your app’s own emails, such as invites | | **Clerk Auth:** your own accounts, branded as your app | Clerk: a verification code when someone signs up with email and password | Yes | | **Your own:** Supabase, Firebase, or code that sends through Resend and the like | Your app or its auth service | Yes, every one | Google, GitHub, Apple and X buttons send no email to sign in, whichever login you use: test those with an account you own. [Login methods explained](https://proxymail.qa/built-with/login-methods) covers what each option does. ## Replit Auth Your users sign in on a Replit-branded page with a Replit account, using Google, GitHub, X, Apple or email. Replit runs that page and sends its emails, such as password resets, so there’s no sign-up email from your app to test. It suits internal tools and apps for other Replit users. For a public app with accounts of its own, ask the Agent for **Clerk Auth** instead. You can still check the emails your app sends itself: invites, notifications and anything you’ve added with an email service. ## Clerk Auth Your app gets its own accounts, separate from Replit, with email and password plus Google, GitHub, Apple or X. Someone who signs up with email gets a **verification code** from Clerk. 1. **Publish first.** Development and production are separate, with separate users, so test on the published app. 2. **Create an address** in Proxy Mail QA, with a generated persona if your form asks for a name. 3. **Sign up with email and password,** then copy the code from the row. 4. **Sign out and back in,** and try any password reset your app offers. 5. **Save the password** on the row so you can sign in as this user again later. **On a custom domain** you bought outside Replit, add the DNS records Replit lists under **Publishing → Domains → Manage** (“Authentication DNS setup required”), so codes come from your domain. They can take up to 48 hours to work. Apps on a `.replit.app` address, or a domain bought through Replit, need nothing extra. ## Your own login If your app uses Supabase, Firebase or its own code with an email service, it sends every login email itself. While you build, Replit runs your app on a development URL connected to your workspace; when you publish, it gets a public address or your custom domain. Login emails should always link to the published one. 1. **Create an address** in Proxy Mail QA. 2. **Sign up on the published app,** not in the workspace preview. 3. **Open the code or link from the row.** Codes have a **Copy** button; links get **Open link** and **Copy link** buttons. 4. **Check where the link goes.** If it points at `localhost` or a private address, we flag it. If it points at the development URL, the base URL isn’t set for the published app. 5. **Test password reset and any invites** the same way, then save the account’s password on the row. ### If the link is wrong Ask the Agent for something specific: “Emails from the published app link to the development URL. Use the published domain as the base URL for all email links, from an environment variable.” If your app uses Supabase Auth, also check its Site URL and Redirect URLs: [here’s how](https://proxymail.qa/solve/localhost-links). ### If emails don’t arrive - Check the app’s email provider is configured on the published app, not just in the workspace. - Check the provider’s logs for a send attempt and any error. - Some providers limit how many emails a new or free account can send, or only send to verified addresses until you set them up (sandbox or test mode). [Test email not arriving?](https://proxymail.qa/troubleshooting) has the fix for each. ## Copy-paste prompts for the Agent Prompt ```text List every email this app sends: sign-up confirmation, verification code, magic link, password reset, invite and email change. For each, tell me what triggers it, who sends it, which URL its link points to, and how long its link or code stays valid. Flag anything that uses localhost or the development URL. ``` Prompt ```text Emails from the published app must link to the published domain. Build every email link from an environment variable for the app's public URL, set it for the published app, and keep the development URL only for the workspace. ``` ## Try it on your next sign-up test Free plan, no credit card. Create an address and watch the code or link arrive. [Create a free account](https://app.proxymail.qa/?mode=signup&from=replit) ## Questions ### Does Replit Auth send emails from my app? No. With Replit Auth, people sign in with a Replit account on a Replit-branded page, and Replit sends the account emails, such as password resets. Your app's own emails, such as invites or notifications, still need checking. ### My verification link opens the development URL. Is that a problem? Yes, for real users. The development URL is tied to your workspace while you build. Emails sent by the published app should link to its published address or your custom domain. ### I made a test account in the workspace, but I can't sign in on the published app. Why? With Clerk Auth, development and production are separate, each with its own users, so accounts made in the workspace don't exist in the published app. Sign up again on the published app with a fresh address. ### Can I test several user roles? Yes. Create a batch of addresses, each with a generated name and username, and use one per role, such as admin, member and guest. Notes and tags keep track of which is which. ## Related guides - [LovableWhich Lovable Cloud logins send email, the Site URL and sender settings, and a check before you launch.](https://proxymail.qa/built-with/lovable) - [BoltTurn on email confirmation, fix the localhost Site URL and test every auth email before you publish.](https://proxymail.qa/built-with/bolt) - [Base44Test the sign-up code, password reset and invites, and every user role, with a test account per role.](https://proxymail.qa/built-with/base44) - [v0Set Supabase’s Site URL and redirects for Vercel deployments, or move Clerk to production, then test every login email.](https://proxymail.qa/built-with/v0) - [Claude CodeCheck the auth emails in apps you build with Anthropic’s coding agent, from localhost to staging.](https://proxymail.qa/built-with/claude-code) - [OpenAI CodexRun the real email flow once before you merge a Codex change that touches sign-up or login.](https://proxymail.qa/built-with/codex) - [QoderCheck the real sign-up, code and reset emails after the agent changes your auth code, or let it check them itself.](https://proxymail.qa/built-with/qoder) - [CursorCheck the real sign-up, magic-link and reset emails after the agent changes your auth code.](https://proxymail.qa/built-with/cursor) - [Google AntigravityKeep unverified Firebase users out, check authorized domains and the sender, and let the agent run the check.](https://proxymail.qa/built-with/antigravity) - [Login methods explainedEmail, codes, magic links, Google and Apple buttons, phone and SSO: what each sends, what breaks and how to test it.](https://proxymail.qa/built-with/login-methods) [See every email testing problem we solve](https://proxymail.qa/solve) Replit is a trademark of Replit, Inc. Clerk is a trademark of Clerk, Inc. Proxy Mail QA is independent and isn’t affiliated with or endorsed by them.