Broadcast Email Deliverability: How to Actually Reach the Inbox

Deliverability is boring until your emails start landing in spam. Then it becomes the most important thing. This guide covers what actually matters for getting broadcast emails into inboxes.

The Basics: DNS Authentication

Three DNS records determine whether email providers trust your messages. Set them up correctly once and mostly forget about them.

SPF (Sender Policy Framework)

SPF tells receiving servers which mail servers are authorized to send email for your domain. It is a TXT record in your DNS.

Your email provider will give you the specific value. It looks something like:

v=spf1 include:_spf.provider.com ~all

Common mistake: Having multiple SPF records. You can only have one. If you use multiple email services, combine them into a single record.

DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to your emails. Receiving servers verify the email was not tampered with and actually came from you.

Your email provider generates DKIM keys. You add their public key as a DNS record (usually CNAME or TXT). They sign outgoing emails with the private key.

DMARC (Domain-based Message Authentication)

DMARC tells receiving servers what to do when SPF or DKIM checks fail. Start with monitoring:

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

After confirming everything works, move to enforcement:

v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com

Sender Reputation

Email providers track your sending reputation. Good reputation equals inbox. Bad reputation equals spam folder.

What Builds Good Reputation

• High open rates: People opening your emails signals they are wanted
• Click engagement: Clicks indicate valuable content
• Replies: The strongest signal of legitimate communication
• Low bounces: You are sending to valid addresses
• Few spam complaints: People are not marking you as junk

What Damages Reputation

• High bounce rates: Sending to invalid addresses looks spammy
• Spam complaints: Even 0.1% complaint rate is concerning
• Spam traps: Old addresses turned into honeypots
• Sudden volume spikes: Going from 100 to 10,000 emails overnight looks suspicious
• Inconsistent patterns: Sporadic large bursts then silence

Practical Guidelines for Broadcasts

Permission is Everything

Only email people who explicitly opted in. Beyond legal requirements, permission-based email performs dramatically better. Purchased lists destroy deliverability fast.

List Hygiene

• Remove bounced addresses immediately
• Consider removing subscribers who have not opened in 6+ months
• Implement double opt-in for new subscribers
• Verify email addresses at signup

Consistent Sending

Regular sending patterns build reputation. Whether weekly or monthly, maintain consistency. Sporadic blasts after months of silence look suspicious.

Easy Unsubscribe

Make unsubscribing one click, no login required. If people cannot unsubscribe easily, they will mark you as spam. That hurts far more than losing a subscriber.

What Your Provider Handles

Good email broadcast services handle most infrastructure concerns:

• IP reputation management
• Bounce processing and suppression
• Feedback loop processing (spam complaints)
• List-Unsubscribe headers
• Automatic removal of problem addresses

Services like Sequenzy, SendGrid, and Mailchimp manage this automatically. Let them handle the infrastructure while you focus on content.

Testing Deliverability

Before major broadcasts:

1. Send test emails to your own Gmail, Outlook, and Yahoo accounts
2. Check if they hit inbox or spam
3. Use tools like Mail-Tester.com for detailed analysis
4. Check Google Postmaster Tools if you send significant volume to Gmail

Warning Signs to Watch

• Open rates dropping suddenly: Might be deliverability, might be content. Investigate.
• Bounce rates above 2%: Something is wrong with your list hygiene.
• Spam complaints above 0.1%: Review your sending practices.
• Emails going to spam for specific providers: Check authentication and content for that provider.

What Does Not Matter Much

Things people worry about that rarely cause actual problems:

• Email length: Gmail does not penalize long emails
• Image-to-text ratio: Old spam filter logic, mostly irrelevant now
• "Spam trigger words": "Free" in your subject line will not tank deliverability
• Send time optimization: Matters more for opens than delivery

Provider-Specific Considerations

Gmail

The largest email provider. Uses sophisticated engagement-based filtering. High engagement with Gmail users improves placement. Register for Google Postmaster Tools for visibility.

Microsoft (Outlook/Hotmail)

Can be strict about new senders. SNDS (Smart Network Data Services) provides reputation visibility. Warm up gradually for Microsoft domains.

Yahoo/AOL

Register for feedback loops to know when users mark you as spam. Generally follows similar patterns to other major providers.

The Bottom Line

Email deliverability comes down to:

1. Proper DNS authentication (SPF, DKIM, DMARC)
2. Using a reputable email broadcast service
3. Only emailing people who opted in
4. Making unsubscribe easy
5. Removing bad addresses promptly
6. Sending consistently over time

That is 90% of deliverability. The remaining 10% is edge cases you will handle as they come up. Focus on the fundamentals and you will reach the inbox.