Bounce Rate

Understanding Bounce Rate

Bounce rate measures the percentage of emails that failed to reach recipients. It's a critical metric that directly impacts your sender reputation and future deliverability.

Healthy Bounce Rate Benchmarks

Types of Bounces

Hard Bounces

Permanent delivery failures that will never succeed:

• Invalid email address
• Domain doesn't exist
• Recipient blocked your domain
• Mailbox permanently disabled

Action: Remove immediately from your list. Never retry.

Soft Bounces

Temporary delivery failures that may succeed later:

• Mailbox full
• Server temporarily unavailable
• Message too large
• Recipient on vacation (auto-reply)

Action: Retry 2-3 times over 24-72 hours. Convert to hard bounce if continues.

Impact of High Bounce Rates

Sender Reputation Damage

ISPs track your bounce rate. High bounces signal that you're not maintaining a clean list, which leads to:

• Lower inbox placement
• More emails going to spam
• Potential blocklisting

Reduced Deliverability

Once your reputation drops, even valid emails to engaged subscribers may not reach the inbox.

Wasted Resources

Sending to invalid addresses wastes API calls, bandwidth, and money.

Causes of High Bounce Rates

Purchased or Scraped Lists

Buying email lists almost always results in high bounce rates. These lists contain:

• Old, abandoned addresses
• Spam traps
• Fake addresses

Never purchase email lists.

Lack of Email Validation

Not validating email addresses at signup allows typos and fake addresses into your database.

Stale Lists

Email addresses decay over time as people change jobs, abandon addresses, or close accounts. A list not mailed in 6+ months will have significant bounces.

Data Import Issues

Importing contacts from other systems can introduce formatting issues or invalid addresses.

Reducing Bounce Rates

1. Validate at Signup

Use real-time email validation to catch invalid addresses before they enter your database:

import { Transactional } from '@transactional/sdk';
 
const client = new Transactional({ apiKey: process.env.TRANSACTIONAL_API_KEY });
 
const { data, error } = await client.emails.validate({
  email: userInput,
});
 
if (!data.valid) {
  // Show error to user
  console.log('Invalid email:', data.reason);
}

2. Use Double Opt-in

Require users to click a confirmation link before adding them to your list. This verifies:

• The email address exists
• The owner has access to it
• They actually want your emails

3. Regular List Cleaning

Periodically validate your entire list and remove invalid addresses:

const results = await client.emails.validateBatch({
  emails: subscriberList,
});
 
const validSubscribers = results.data.filter(r => r.valid);

4. Monitor and Remove

• Remove hard bounces immediately
• Remove soft bounces after 3 failed attempts
• Remove unengaged subscribers after 6-12 months

5. Segment by Engagement

Send to engaged subscribers more frequently. Reduce frequency or re-engagement campaigns for inactive subscribers before removing them.

Bounce Handling with Transactional

Transactional automatically handles bounces for you:

Automatic Suppression

Hard bounces are automatically added to your suppression list. Subsequent sends to that address are blocked before they leave our servers.

Webhook Notifications

Receive real-time notifications when bounces occur:

// Webhook payload for bounce event
{
  "type": "email.bounced",
  "data": {
    "email_id": "msg_abc123",
    "recipient": "invalid@example.com",
    "bounce_type": "hard",
    "bounce_reason": "mailbox_not_found",
    "timestamp": "2024-01-15T10:30:00Z"
  }
}

Bounce Reports

Access detailed bounce reports in your dashboard showing:

• Bounce rate trends over time
• Breakdown by bounce type
• Top bouncing domains
• Bounced addresses for removal

Industry Benchmarks

Your target should be below 0.5% for transactional emails and below 2% for marketing emails.