What is Email Deliverability?
You can write the perfect cold email. But if it lands in spam, nobody will ever see it.
Email deliverability is the science of getting your messages into the primary inbox—not the promotions tab, not the spam folder. It's the foundation everything else depends on.
Email Deliverability Explained
Deliverability is the percentage of your emails that actually reach the recipient's inbox. It's determined by a complex mix of technical factors, sender reputation, and content signals.
Think of it like a credit score for email. Good behavior over time builds trust. Bad behavior—or even the appearance of bad behavior—destroys it.
Why Deliverability Matters
Spam folder = invisible — 99% of spam folder emails are never seen. Your brilliant copy doesn't matter if it's not delivered.
Reputation is cumulative — Every email you send affects your sender reputation. Poor deliverability today makes tomorrow worse.
Inbox providers are getting smarter — Google, Microsoft, and others continuously improve spam detection. What worked last year may not work today.
The Three Pillars of Deliverability
1. Technical Authentication
Your domain needs proper authentication records to prove you're a legitimate sender:
SPF (Sender Policy Framework) — Specifies which servers can send email for your domain
DKIM (DomainKeys Identified Mail) — Cryptographic signature proving the email wasn't tampered with
DMARC (Domain-based Message Authentication) — Policy telling receivers how to handle authentication failures
2. Sender Reputation
Inbox providers track your sending behavior over time:
Bounce rates — Too many invalid addresses signals poor list hygiene
Spam complaints — Recipients marking you as spam is the fastest way to tank reputation
Engagement metrics — Opens, replies, and clicks signal legitimate mail
Sending patterns — Sudden volume spikes look suspicious
3. Content Signals
What you say and how you say it matters:
Spam trigger words — Certain phrases increase spam probability
Link quality — Spammy or shortened URLs hurt deliverability
HTML/text ratio — Image-heavy emails often get filtered
Personalization — Identical mass emails are obvious to filters
Common Deliverability Mistakes
Sending from your main domain — If cold email goes wrong, your entire company's email reputation suffers
Skipping warmup — New domains/inboxes need gradual volume increases
Ignoring bounce rates — Clean your lists or pay the reputation price
Sending too much too fast — Volume spikes trigger spam filters
How BuzzLead Handles Deliverability
We obsess over deliverability so you don't have to:
39-55 dedicated sending domains — Isolated from your main brand
Proper authentication on every domain — SPF, DKIM, DMARC configured correctly
Inbox warmup protocols — Gradual reputation building before any outreach
Continuous monitoring — We catch and fix issues before they become problems
Frequently Asked Questions
How do I check my current deliverability?
Tools like GlockApps, Mail-Tester, and MXToolbox can test your setup. But the real measure is inbox placement rates from actual sends—which requires proper tracking infrastructure.
Can I fix deliverability problems on my own?
Technical setup (SPF/DKIM/DMARC) is straightforward. Reputation repair is harder—it takes time and careful sending practices. If you've already damaged a domain, it's often faster to start fresh.
Why do I need separate domains for cold email?
Cold email carries inherent reputation risk. If something goes wrong, you don't want your main company domain (the one your employees use) to suffer. Separate domains create isolation.
How long does email warmup take?
Proper warmup takes 2-4 weeks. Rushing it is one of the most common mistakes—and one of the hardest to recover from.