Why do emails work in development but not production?

Production requires proper DNS configuration (SPF/DKIM records) and a verified sender domain. Development mode uses Supabase default email service which is less strict.

How long does it take for confirmation emails to arrive?

With proper SMTP configuration, emails should arrive within 1-2 minutes. If using default Supabase email, it can take 5-10 minutes or fail entirely.

Can I disable email confirmation?

Yes, but not recommended for production. Go to Dashboard > Authentication > Settings > Enable email confirmations (toggle off). This creates security risks.

What if users never receive the email?

Implement a resend confirmation feature and provide alternative verification methods (phone, social auth). Always check spam folders first.

How do I test email sending locally?

Use a service like Mailtrap or MailHog for local testing. Configure SMTP to point to these services during development.

Supabase Email Confirmation Not Sending: 5 Fixes (2026)

Supabase Email Confirmation Not Sending Troubleshooting Guide#

The fix, in order of likelihood: Supabase's built-in SMTP is rate-limited to a handful of emails per hour and only reaches accounts on your project's team — the moment you test with a real user address, it silently stops sending. Configure a custom SMTP provider (Resend, Postmark, SES) in Dashboard → Authentication → Email Templates → SMTP Settings first; that alone fixes it for most people. If the email still doesn't arrive, the 4 next-most-common causes — broken template links, missing SPF/DKIM records, an already-confirmed user, and dev-mode rate limits — are covered below in the order to check them.

This article is part of our comprehensive Supabase Authentication & Authorization Patterns guide.

Why Supabase Email Confirmations Fail#

There are 5 main reasons why confirmation emails don't send:

Development Mode Limitations - Supabase free tier has email rate limits
SMTP Not Configured - Default email service is unreliable
Email Template Issues - Broken confirmation links or template errors
Domain/DNS Problems - SPF/DKIM records not configured
User Already Confirmed - Email was already verified

Quick Diagnostic Checklist#

Before diving into fixes, run through this checklist:

bash

## Check Supabase logs
## Go to: Dashboard > Logs > Auth Logs
## Look for: "email_confirmation_sent" or error messages
 
## Check user status in database
SELECT email, email_confirmed_at, confirmation_token 
FROM auth.users 
WHERE email = 'user@example.com';
 
## Verify SMTP settings
## Go to: Dashboard > Authentication > Email Templates
## Check: SMTP settings are configured

Solution 1: Configure Custom SMTP (Recommended)#

The default Supabase email service is unreliable. Use a custom SMTP provider:

Step 1: Choose an SMTP Provider#

Best options for production:

SendGrid - 100 emails/day free, reliable
Resend - Modern API, great DX
AWS SES - Cheapest for high volume
Mailgun - Good deliverability

Step 2: Configure SMTP in Supabase#

typescript

// 1. Go to Supabase Dashboard > Project Settings > Auth
// 2. Scroll to "SMTP Settings"
// 3. Enable "Enable Custom SMTP"
 
// Example SendGrid Configuration:
Host: smtp.sendgrid.net
Port: 587
Username: apikey
Password: YOUR_SENDGRID_API_KEY
Sender email: noreply@iloveblogs.blog
Sender name: Your App Name

Step 3: Verify SMTP Connection#

typescript

// Test email sending from Supabase Dashboard
// Go to: Authentication > Email Templates
// Click: "Send test email"
// Check: Email arrives in inbox (not spam)

Step 4: Update Environment Variables#

bash

## .env.local
NEXT_PUBLIC_SUPABASE_URL=your-project-url
NEXT_PUBLIC_SUPABASE_ANON_KEY=your-anon-key
 
## For custom email templates
SMTP_HOST=smtp.sendgrid.net
SMTP_PORT=587
SMTP_USER=apikey
SMTP_PASS=your-api-key

Solution 2: Fix Email Template Configuration#

Check Confirmation URL#

The confirmation link must point to your application:

typescript

// Supabase Dashboard > Authentication > URL Configuration
// Site URL: https://www.iloveblogs.blog
// Redirect URLs: https://www.iloveblogs.blog/auth/callback
 
// Email template should use: {{ .ConfirmationURL }}
// NOT: {{ .SiteURL }}/auth/confirm?token={{ .Token }}

Update Email Template#

html

<!-- Go to: Dashboard > Authentication > Email Templates > Confirm signup -->
<h2>Confirm your signup</h2>
<p>Follow this link to confirm your account:</p>
<p><a href="{{ .ConfirmationURL }}">Confirm your email</a></p>
<p>Or copy and paste this URL into your browser:</p>
<p>{{ .ConfirmationURL }}</p>

Handle Confirmation in Next.js#

@supabase/auth-helpers-nextjs is archived — do not start new code with it. Use @supabase/ssr instead (createServerClient for Route Handlers, Server Components, and Server Actions; createBrowserClient for Client Components). In Next.js 15+ cookies() is async, so you await it before building the client.

typescript

// app/auth/callback/route.ts
import { createServerClient } from '@supabase/ssr'
import { cookies } from 'next/headers'
import { NextResponse } from 'next/server'
 
export async function GET(request: Request) {
  const requestUrl = new URL(request.url)
  const token_hash = requestUrl.searchParams.get('token_hash')
  const type = requestUrl.searchParams.get('type')
  const next = requestUrl.searchParams.get('next') ?? '/'
 
  if (token_hash && type) {
    const cookieStore = await cookies()
    const supabase = createServerClient(
      process.env.NEXT_PUBLIC_SUPABASE_URL!,
      process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
      {
        cookies: {
          getAll() {
            return cookieStore.getAll()
          },
          setAll(cookiesToSet) {
            cookiesToSet.forEach(({ name, value, options }) =>
              cookieStore.set(name, value, options)
            )
          },
        },
      }
    )
 
    const { error } = await supabase.auth.verifyOtp({
      type: type as any,
      token_hash,
    })
 
    if (!error) {
      return NextResponse.redirect(new URL(next, request.url))
    }
  }
 
  // Return error page
  return NextResponse.redirect(new URL('/auth/error', request.url))
}

Solution 3: Configure DNS Records (Production)#

For production, configure SPF and DKIM records:

SPF Record#

dns

## Add TXT record to your domain:
Type: TXT
Name: @
Value: v=spf1 include:sendgrid.net ~all
 
## For SendGrid, check their documentation for exact value

DKIM Record#

dns

## SendGrid provides DKIM records in their dashboard
## Add 3 CNAME records they provide
## Example:
Type: CNAME
Name: s1._domainkey
Value: s1.domainkey.u12345.wl.sendgrid.net

Verify DNS Configuration#

bash

## Check SPF record
nslookup -type=TXT iloveblogs.blog
 
## Check DKIM record
nslookup -type=CNAME s1._domainkey.iloveblogs.blog
 
## Test email deliverability
## Use: mail-tester.com

Solution 4: Handle Rate Limits#

Supabase has email rate limits on free tier:

typescript

// Implement retry logic for email sending (client component)
import { createBrowserClient } from '@supabase/ssr'
 
async function sendConfirmationEmail(email: string) {
  const supabase = createBrowserClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!
  )
 
  try {
    const { error } = await supabase.auth.signUp({
      email,
      password: 'user-password',
      options: {
        emailRedirectTo: `${window.location.origin}/auth/callback`,
      },
    })
 
    if (error) {
      // Check if rate limit error
      if (error.message.includes('rate limit')) {
        // Wait and retry
        await new Promise(resolve => setTimeout(resolve, 5000))
        return sendConfirmationEmail(email)
      }
      throw error
    }
 
    return { success: true }
  } catch (error) {
    console.error('Email send failed:', error)
    return { success: false, error }
  }
}

Solution 5: Resend Confirmation Email#

Allow users to resend confirmation:

typescript

// app/api/resend-confirmation/route.ts
import { createServerClient } from '@supabase/ssr'
import { cookies } from 'next/headers'
import { NextResponse } from 'next/server'
 
export async function POST(request: Request) {
  const { email } = await request.json()
  const cookieStore = await cookies()
  const supabase = createServerClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
    {
      cookies: {
        getAll() {
          return cookieStore.getAll()
        },
        setAll(cookiesToSet) {
          cookiesToSet.forEach(({ name, value, options }) =>
            cookieStore.set(name, value, options)
          )
        },
      },
    }
  )
 
  const { error } = await supabase.auth.resend({
    type: 'signup',
    email,
    options: {
      emailRedirectTo: `${process.env.NEXT_PUBLIC_SITE_URL}/auth/callback`,
    },
  })
 
  if (error) {
    return NextResponse.json({ error: error.message }, { status: 400 })
  }
 
  return NextResponse.json({ message: 'Confirmation email sent' })
}

Frontend Component#

typescript

'use client'
 
import { useState } from 'react'
 
export function ResendConfirmation({ email }: { email: string }) {
  const [loading, setLoading] = useState(false)
  const [message, setMessage] = useState('')
 
  async function handleResend() {
    setLoading(true)
    
    const response = await fetch('/api/resend-confirmation', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ email }),
    })
 
    const data = await response.json()
    setMessage(data.message || data.error)
    setLoading(false)
  }
 
  return (
    <div>
      <p>Didn't receive the email?</p>
      <button onClick={handleResend} disabled={loading}>
        {loading ? 'Sending...' : 'Resend confirmation email'}
      </button>
      {message && <p>{message}</p>}
    </div>
  )
}

Common Mistakes#

Mistake #1: Not checking spam folder - Always check spam/junk folders first
Mistake #2: Using default Supabase email - Configure custom SMTP for reliability
Mistake #3: Wrong redirect URL - Ensure Site URL matches your domain exactly
Mistake #4: Missing DNS records - SPF/DKIM required for production
Mistake #5: Not handling errors - Always show user-friendly error messages

Conclusion#

Email confirmation issues in Supabase are usually caused by SMTP configuration, template problems, or DNS settings. The most reliable solution is configuring custom SMTP with a provider like SendGrid or Resend, along with proper DNS records for production.

Follow the solutions above in order: configure SMTP first, then fix templates, add DNS records, and implement resend functionality. Test thoroughly in development before deploying to production.

Monitor your email deliverability using services like mail-tester.com and always provide users with a way to resend confirmation emails if needed.

Supabase Email Confirmation Not Sending: 5 Fixes (2026)

Supabase Email Confirmation Not Sending Troubleshooting Guide#

Why Supabase Email Confirmations Fail#

Quick Diagnostic Checklist#

Solution 1: Configure Custom SMTP (Recommended)#

Step 1: Choose an SMTP Provider#

Step 2: Configure SMTP in Supabase#

Step 3: Verify SMTP Connection#

Step 4: Update Environment Variables#

Solution 2: Fix Email Template Configuration#

Check Confirmation URL#

Update Email Template#

Handle Confirmation in Next.js#

Solution 3: Configure DNS Records (Production)#

SPF Record#

DKIM Record#

Verify DNS Configuration#

Solution 4: Handle Rate Limits#

Solution 5: Resend Confirmation Email#

Frontend Component#

Common Mistakes#

Conclusion#

Frequently Asked Questions

Why do emails work in development but not production?

How long does it take for confirmation emails to arrive?

Can I disable email confirmation?

What if users never receive the email?

How do I test email sending locally?

Written by

Mahdi Br

Supabase Auth Session Disappears on Refresh? Fix (2026)

Supabase AuthSessionMissingError in Middleware: 5 Fixes

Supabase Auth Callback Redirect Not Working? Next.js Fix

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Supabase Email Confirmation Not Sending: 5 Fixes (2026)

Supabase Email Confirmation Not Sending Troubleshooting Guide#

Why Supabase Email Confirmations Fail#

Quick Diagnostic Checklist#

Solution 1: Configure Custom SMTP (Recommended)#

Step 1: Choose an SMTP Provider#

Step 2: Configure SMTP in Supabase#

Step 3: Verify SMTP Connection#

Step 4: Update Environment Variables#

Solution 2: Fix Email Template Configuration#

Check Confirmation URL#

Update Email Template#

Handle Confirmation in Next.js#

Solution 3: Configure DNS Records (Production)#

SPF Record#

DKIM Record#

Verify DNS Configuration#

Solution 4: Handle Rate Limits#

Solution 5: Resend Confirmation Email#

Frontend Component#

Common Mistakes#

Related Articles#

Conclusion#

Frequently Asked Questions

Why do emails work in development but not production?

How long does it take for confirmation emails to arrive?

Can I disable email confirmation?

What if users never receive the email?

How do I test email sending locally?

Written by

Mahdi Br

Continue Reading

Supabase Auth Session Disappears on Refresh? Fix (2026)

Supabase AuthSessionMissingError in Middleware: 5 Fixes

Supabase Auth Callback Redirect Not Working? Next.js Fix

Browse by Topic

PostgreSQL

Next.js

Automation

DevOps

Supabase

TypeScript