What Is Email Deliverability?
At a glance, it might seem like if your email gets "delivered," you're winning. But that's not quite right.
Email deliverability means your email successfully lands in the recipient's inbox—not just their spam folder or rejected queue.
It's the invisible yet critical metric that:
- Impacts your open and click rates
- Affects sender reputation and domain health
- Determines your long-term ROI on email marketing
Deliverability Rate Formula (And How It's Calculated)
Deliverability rate answers: Of the emails I sent, how many made it into the inbox?
The Deliverability Formula:
Deliverability Rate = (Inboxed Emails ÷ Total Emails Sent) × 100Example:
You send 10,000 emails → 9,300 hit the inbox
(9,300 / 10,000) × 100 = 93% Deliverability⚠️ Important:
This is not the same as delivery rate, which just means the message wasn't bounced. Your email can be "delivered"—but straight to spam.
Step-by-Step: How to Audit Your Deliverability
Here's a hands-on workflow:
Start With a Clean List
Run your list through a validator like Lero to:
- Remove dead or invalid addresses
- Flag disposable or trap-prone domains
- Prevent bounce spikes before testing
Authenticate Your Domain
Use SPF, DKIM, and DMARC authentication.
Send a Test Campaign
Use GlockApps or seed-list testing to check inbox placement.
Why List Hygiene Directly Affects Your Rate
Every bad email you send chips away at your sender trust.
Lero's real-time email validator:
- Removes dead, typo'd, and disposable emails
- Flags catch-all or MX-missing domains
- Prevents spam traps that silently degrade your score
💡 Want a foundation guide? See Email Validation 2025
📥 Need help with email setup? Read Deliverability 101
Final Thoughts + Fix Your Foundation
You can't fix what you can't measure.
Deliverability isn't just a metric—it's your gateway to growth.
📊 Here's your next move:
- • Validate your list with Lero → 500 free credits
- • Read the Email Validation Guide
- • Fix setup with Deliverability 101