Effective Bounce Handling Strategies

Bounces are inevitable in email, but how you handle them determines your sender reputation and long-term deliverability. Here's a comprehensive guide to bounce management.

Understanding Bounce Types

Hard Bounces

Permanent delivery failures that won't resolve with retries:

• **Invalid address**: The email address doesn't exist
• **Domain doesn't exist**: The recipient's domain is invalid
• **Blocked**: The recipient has blocked your domain

Action: Remove immediately from your list. Never retry.

Soft Bounces

Temporary delivery failures that might succeed later:

• **Mailbox full**: Recipient's inbox is over quota
• **Server unavailable**: Temporary outage
• **Message too large**: Email exceeds size limits
• **Rate limited**: Too many emails sent too quickly

Action: Retry with exponential backoff. Remove after 3-5 consecutive soft bounces.

Implementing Bounce Handling

Webhook-Based Processing

Postalynk sends bounce notifications via webhooks:

app.post('/webhooks/email', async (req, res) => {

if (event === 'bounced') { await handleBounce(data); }

res.json({ received: true }); });

async function handleBounce(bounceData) { const { recipient, bounceType, bounceCode, messageId } = bounceData;

// Log for analysis await db.bounces.create({ email: recipient, type: bounceType, code: bounceCode, messageId, timestamp: new Date(), });

// Take action based on type if (bounceType === 'hard') { await removeFromAllLists(recipient); await notifyRelevantTeam(bounceData); } else { await trackSoftBounce(recipient); } } ```

Soft Bounce Escalation

Track soft bounces and escalate to suppression:

async function trackSoftBounce(email) {
  const key = `soft-bounce:${email}`;
  const count = await redis.incr(key);

if (count >= 5) { // Too many soft bounces - treat as hard bounce await removeFromAllLists(email); await redis.del(key); } } ```

Building a Suppression List

What to Suppress

Your suppression list should include:

1. **Hard bounces**: Immediate suppression
2. **Spam complaints**: Immediate suppression
3. **Unsubscribes**: Immediate suppression
4. **Repeated soft bounces**: After threshold reached

Suppression List Structure

CREATE TABLE email_suppressions (
  email VARCHAR(255) PRIMARY KEY,
  reason ENUM('hard_bounce', 'soft_bounce', 'spam', 'unsubscribe'),
  source VARCHAR(100), -- Which list/campaign
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Check Before Every Send

async function sendEmail(params) {
  // Check suppression list first
  const suppressed = await db.emailSuppressions.findUnique({
    where: { email: params.to },

if (suppressed) { logger.info('Email suppressed', { email: params.to, reason: suppressed.reason }); return { suppressed: true, reason: suppressed.reason }; }

return postalynk.send(params); } ```

Analyzing Bounce Patterns

Monitor Bounce Rates

Track bounces by:

• **Domain**: Identify problematic recipient domains
• **Campaign**: Some content triggers more bounces
• **List age**: Older lists have more bounces
• **Source**: Where did these emails come from?

Healthy Benchmarks

Investigate Spikes

If bounces suddenly increase:

1. Check for list imports (new addresses often have issues)
2. Review recent DNS/infrastructure changes
3. Verify you haven't been blacklisted
4. Check if a major ISP is having issues

Cleaning Your Lists

Regular Hygiene

Schedule regular list cleaning:

// Monthly job to clean inactive subscribers
async function cleanInactiveSubscribers() {
  const sixMonthsAgo = new Date();

const inactive = await db.subscribers.findMany({ where: { lastEngagement: { lt: sixMonthsAgo }, status: 'active', }, });

// Option 1: Move to re-engagement campaign await moveToReEngagementList(inactive);

// Option 2: Suppress immediately // await suppressEmails(inactive.map(s => s.email)); } ```

Email Verification

Before importing lists, verify emails:

async function verifyAndImportList(emails) {
  const results = {
    valid: [],
    invalid: [],
    risky: [],

for (const email of emails) { const verification = await emailVerifier.verify(email);

if (verification.isValid) { results.valid.push(email); } else if (verification.isRisky) { results.risky.push(email); } else { results.invalid.push(email); } }

// Only import valid emails await importSubscribers(results.valid);

return results; } ```

Recovery Strategies

After a Bounce Spike

1. **Stop sending** to the affected segment
2. **Analyze** the bounce data for patterns
3. **Clean** the affected list
4. **Verify** remaining addresses if needed
5. **Resume slowly** with engaged users first

Reputation Recovery

If your bounce rate damaged your reputation:

1. Reduce sending volume temporarily
2. Send only to highly engaged users
3. Monitor delivery metrics closely
4. Gradually increase volume over weeks

Conclusion

Bounce handling isn't glamorous, but it's essential for email success. Implement proper suppression lists, monitor bounce rates, and clean your lists regularly.

Postalynk handles bounce processing automatically and provides detailed bounce analytics. Set up webhook handlers, and we'll give you real-time bounce notifications to keep your lists healthy.