How to Set Up Email Sending for Your SaaS (2026)

Your SaaS needs email: welcome messages, password resets, receipts, notifications, and eventually marketing. Here's how to set it up properly — DNS, deliverability, templates, and the right tools.

The Two Types of Email

Transactional Email

Triggered by user actions: welcome emails, password resets, receipts, notifications. Must be fast and reliable. Users expect these immediately.

Marketing Email

Newsletters, product updates, promotions. Sent in bulk. Needs unsubscribe links and CAN-SPAM compliance.

Use different services for each. Transactional: Resend or Postmark. Marketing: Loops, beehiiv, or ConvertKit.

Step 1: Choose a Transactional Email Provider

Provider	Free Tier	Pricing	Best For
Resend	3,000/mo	$20/mo (50K)	Developer DX
Postmark	100/mo	$15/mo (10K)	Deliverability
SendGrid	100/day	$20/mo (50K)	Scale
AWS SES	62K/mo (from EC2)	$0.10/1K	Budget at scale

Recommendation: Resend for most SaaS apps. Best DX, React Email support, generous free tier.

Step 2: DNS Setup (Critical for Deliverability)

SPF Record

Tells email servers which services can send on your behalf:

Type: TXT
Name: @
Value: v=spf1 include:resend.com ~all

DKIM Record

Cryptographic signature proving emails are from you. Your email provider gives you a DKIM record to add:

Type: CNAME
Name: resend._domainkey
Value: (provided by Resend)

DMARC Record

Policy for handling failed SPF/DKIM checks:

Type: TXT
Name: _dmarc
Value: v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com

Why DNS Matters

Without proper DNS records, your emails land in spam. Gmail, Outlook, and Yahoo require SPF, DKIM, and DMARC in 2026. This isn't optional.

Step 3: Set Up Resend

npm install resend

// src/lib/email.ts
import { Resend } from 'resend'

export const resend = new Resend(process.env.RESEND_API_KEY)

export async function sendEmail({
  to,
  subject,
  html,
}: {
  to: string
  subject: string
  html: string
}) {
  const { data, error } = await resend.emails.send({
    from: 'YourApp <hello@yourdomain.com>',
    to,
    subject,
    html,
  })

  if (error) {
    console.error('Email send failed:', error)
    throw error
  }

  return data
}

Step 4: Email Templates with React Email

Build emails with React components instead of raw HTML:

npm install @react-email/components

// src/emails/welcome.tsx
import { Html, Head, Body, Container, Text, Button, Hr } from '@react-email/components'

export function WelcomeEmail({ name, loginUrl }: { name: string; loginUrl: string }) {
  return (
    <Html>
      <Head />
      <Body style={{ fontFamily: 'sans-serif', backgroundColor: '#f4f4f5' }}>
        <Container style={{ maxWidth: '600px', margin: '0 auto', padding: '20px' }}>
          <Text style={{ fontSize: '24px', fontWeight: 'bold' }}>
            Welcome to YourApp, {name}! 🎉
          </Text>
          <Text>
            Your account is ready. Here's what to do next:
          </Text>
          <Text>1. Create your first project</Text>
          <Text>2. Invite your team</Text>
          <Text>3. Start building</Text>
          <Hr />
          <Button
            href={loginUrl}
            style={{
              backgroundColor: '#000',
              color: '#fff',
              padding: '12px 24px',
              borderRadius: '6px',
              textDecoration: 'none',
            }}
          >
            Go to Dashboard
          </Button>
        </Container>
      </Body>
    </Html>
  )
}

Send with React Email + Resend

import { WelcomeEmail } from '@/emails/welcome'
import { render } from '@react-email/render'

await resend.emails.send({
  from: 'YourApp <hello@yourdomain.com>',
  to: user.email,
  subject: 'Welcome to YourApp!',
  react: <WelcomeEmail name={user.name} loginUrl="https://yourapp.com/dashboard" />,
})

Step 5: Essential Email Flows

1. Welcome Email (on signup)

Trigger: User creates account Content: Welcome message, getting started steps, CTA to dashboard

2. Email Verification

Trigger: User signs up (if not using Clerk/Auth0 which handle this) Content: Verification link

3. Password Reset

Trigger: User requests reset Content: Reset link (expires in 1 hour)

4. Payment Receipt

Trigger: Stripe webhook (invoice.payment_succeeded) Content: Amount, plan, next billing date, invoice PDF link

5. Usage Alert

Trigger: User approaches plan limit Content: Current usage, limit, upgrade CTA

6. Trial Ending

Trigger: 3 days before trial expires Content: Trial end date, what they'll lose, upgrade CTA

Deliverability Checklist

Domain Warming

New domains have no email reputation. ISPs are suspicious of unknown senders. Warm up gradually:

Week 1: 50-100 emails/day (transactional only)
Week 2: 200-500 emails/day
Week 3: 500-1,000 emails/day
Week 4+: Normal volume

Don't blast 10,000 marketing emails from a new domain on day one. You'll end up in spam.

FAQ

Can I use Gmail/Outlook to send transactional email?

No. Gmail limits you to 500 emails/day and doesn't support custom domains properly. Use a dedicated service.

How do I avoid the spam folder?

DNS records (SPF, DKIM, DMARC), custom domain, warm up gradually, don't use spam trigger words, include an unsubscribe link, and send emails people actually want.

Should I use the same service for transactional and marketing?

No. Use Resend/Postmark for transactional (fast, reliable). Use Loops/beehiiv for marketing (list management, analytics). This protects your transactional deliverability.

How much does email cost at scale?

With Resend: 50K emails/month = $20. With AWS SES: 100K emails/month = $10. Email is cheap.

Bottom Line

Set up DNS records (SPF, DKIM, DMARC) on day one. Use Resend + React Email for beautiful transactional emails. Keep transactional and marketing email separate. Warm up your domain gradually. Total setup time: 2-3 hours for a production-ready email system.