Email Deliverability Score

The deliverability score measures the health of your email sending reputation on a scale of 0-100. This score helps you identify potential issues before they impact your sender reputation with email providers.

Score Calculation

Your deliverability score starts at 100 points and is reduced based on negative engagement signals:

Bounce Rate Penalty

Each 1% bounce rate = -5 points

Bounces occur when emails cannot be delivered to a recipient's inbox. There are two types:

• Hard Bounces: Permanent delivery failures (invalid email address, domain doesn't exist)
• Soft Bounces: Temporary delivery issues (mailbox full, server temporarily unavailable)

Example: If you send 1,000 emails and 20 bounce (2% bounce rate), you lose 10 points.

Why it matters: High bounce rates signal to email providers that you're sending to invalid addresses, damaging your sender reputation.

Complaint Rate Penalty

Each 0.1% complaint rate = -5 points

Complaints occur when recipients mark your email as spam or junk.

Formula: (complaints / total sent) × 100

Example: If you send 10,000 emails and 20 are marked as spam (0.2% complaint rate), you lose 10 points.

Why it matters: Spam complaints are the strongest negative signal. Email providers heavily penalize senders with high complaint rates, potentially blocking all future emails.

Understanding the Metrics

Sent (In Transit)

Emails that have been accepted by the email provider but not yet delivered to the recipient's inbox. This includes:

• Emails being processed by the recipient's mail server
• Emails in queue waiting for delivery
• Pending emails that haven't received a final status

Delivered

Emails successfully delivered to the recipient's mail server. This doesn't guarantee inbox placement - the email could still end up in spam.

Note: Delivered ≠ Inbox placement. A "delivered" email may still land in the spam folder.

Bounced

Emails that were rejected and couldn't be delivered. Lumail automatically tracks both hard and soft bounces.

Best practice: Remove hard bounced addresses from your list immediately to maintain a healthy sender reputation.

Complained

Recipients who marked your email as spam or junk through their email client.

Critical threshold: Even 0.1% complaint rate can trigger deliverability issues. Keep this metric as close to 0% as possible.

Score Interpretation

Score Range	Status	Action Required
95-100	Excellent (🟢)	No action needed. Maintain current practices.
80-94	Good (🔵)	Monitor metrics. Consider list cleaning if score drops.
60-79	Needs Attention (🟡)	Review bounce and complaint rates. Clean your list.
0-59	Critical (🔴)	Immediate action required. Pause sending and investigate.

Improving Your Score

Reduce Bounce Rate

1. Use double opt-in to verify email addresses before adding to your list
2. Implement email verification at signup to catch typos and invalid addresses
3. Regularly clean your list by removing hard bounces immediately
4. Monitor engagement and remove inactive subscribers (no opens/clicks in 6+ months)

Reduce Complaint Rate

1. Set clear expectations during signup about email frequency and content
2. Make unsubscribe easy with a prominent link in every email
3. Segment your audience to send more relevant content
4. Send from a recognizable sender name that subscribers will recognize
5. Avoid spam trigger words in subject lines and content
6. Honor unsubscribe requests immediately (within 24 hours)

Monitoring Your Score

Your deliverability score is calculated in real-time based on your recent email activity. Check your dashboard regularly to:

• Identify trends before they become problems
• Validate the impact of list cleaning efforts
• Compare performance across different campaigns
• Monitor the health of your sender reputation

Industry Benchmarks

For comparison, here are typical industry ranges:

• Bounce Rate: < 2% is excellent, 2-5% needs attention, > 5% is critical
• Complaint Rate: < 0.1% is excellent, 0.1-0.3% needs attention, > 0.3% is critical

Remember: These are averages. Your specific industry or audience may have different norms. Focus on trends rather than absolute numbers.

Technical Details

The deliverability score is calculated using the formula:

score = 100 - (bounceRate × 5) - (complainRate × 50)
score = Math.max(0, Math.min(100, Math.round(score)))

Where:

• bounceRate = (bounced emails / total sent) × 100
• complainRate = (complained emails / total sent) × 100

This heavily weights spam complaints (50× multiplier) because they have the most severe impact on deliverability.

Related Documentation

• Content Deliverability Checker - Pre-send content analysis
• Engagement Score - Track subscriber engagement
• Email Domains - Configure SPF, DKIM, DMARC
• Subscriber Events - View bounce and complaint events