How to Run an Email Deliverability Test: A Proven Checklist

Here's a surprising fact: only 79.6% of legitimate emails actually reach their intended destination. This means 3 out of every 20 important messages you send might never land in your recipients' inboxes.

Most successful businesses maintain email deliverability rates between 85% and 95%, but many companies find these numbers hard to achieve. Even transactional emails face this challenge, with typical inbox placement rates around 78.8%.

A solid email deliverability checklist is a vital part of your 2025 email strategy. Your messages might end up in spam folders or bounce back, or worse - get low engagement metrics. We'll help you improve your email deliverability and ensure your messages reach their destination.

Want to boost your inbox placement rates and keep your important communications flowing? Let's tuck into our complete guide to fix your email deliverability problems once and for all.

Common Email Deliverability Problems

Email deliverability faces three big challenges that affect inbox placement rates. A good understanding of these problems helps you create an effective email deliverability checklist for 2025.

Spam folder placement

The biggest problem with deliverability remains spam folder placement, affecting nearly half of all email senders. Your emails might reach the recipient's server but fail to land in the primary inbox.

These common triggers send emails to spam:

• Failed authentication (DMARC, DKIM, or SPF)
• Damaged domain or IP reputation
• Inconsistent sending patterns
• Missing unsubscribe links

Sending too many emails quickly can trigger ISP rate limits. On top of that, it affects deliverability substantially when spam complaints exceed 0.3%, which could land you on an IP blocklist.

High bounce rates

Bounce rates tell you a lot about email deliverability health. Your bounce rate should stay below 2% to meet industry standards. Numbers above this threshold point to serious deliverability problems that need quick fixes.

Your email campaigns face two types of bounces:

1. Hard bounces: Permanent delivery failures from invalid addresses or non-existent mailboxes
2. Soft bounces: Temporary issues like full inboxes or server timeouts

A clean email list makes everything work better, especially since email lists lose 25-30% of contacts yearly. Regular list cleanup prevents most deliverability issues.

Low engagement metrics

Low engagement metrics point to deliverability problems. Your emails might land in spam folders or subscribers might ignore irrelevant content. Inbox providers see lack of interaction as unwanted communication.

Poor engagement shows up as:

• Declining open rates
• Reduced click-through rates
• Increased spam complaints
• Higher unsubscribe rates

Email providers look at engagement to determine sender reputation and inbox placement. To cite an instance, a subscriber who gets 50 emails but opens none sends a red flag to inbox providers about poor practices. This behavior pushes more emails to spam folders, creating a downward spiral in deliverability.

Check Your Current Deliverability Status

A detailed email deliverability test before launching any campaign will help you spot potential risks that could hurt your success rate. You'll learn about ways to optimize when you understand your current deliverability status.

Run an email deliverability test

You need specialized tools that simulate real-life conditions to test email deliverability effectively. Your testing should review multiple aspects of your email infrastructure instead of relying on simple spam checks.

Send your test emails through your actual email sending service to get accurate results. This reflects real campaign conditions and includes tracking pixels and HTML elements that your email service provider adds automatically.

The average deliverability rate across email service providers is 83.1%. You should measure your performance against this number to spot areas needing improvement. We tested deliverability with email providers that your recipients use most often, especially Google Workspace and Office 365.

Modern deliverability testing tools analyze these significant components:

• Authentication verification (SPF, DKIM, DMARC)
• Domain and IP reputation checks
• Content analysis for spam triggers
• Inbox placement tracking
• Blacklist monitoring

Analyze key metrics

These metrics will tell you about your email program's health after your deliverability test:

Your domain health score shows how well your sender domain is configured technically. A score between 75-100% means your DNS records are set up correctly. This score affects how often you reach recipient inboxes.

The email placement score shows where your messages end up. Watch for these indicators:

• Inbox placement rate above 90% means excellent deliverability
• This is a big deal as it means that spam rates over 5-10% point to serious problems
• Category placement (like Gmail's Promotions tab) suggests you need to optimize content

Your sender reputation determines email success. This score combines many factors, including engagement metrics and sending patterns. Deliverability problems often follow a dropping sender score.

Regular deliverability tests work better than waiting for problems to appear. This approach helps maintain consistent inbox placement and prevents reputation damage that could hurt future campaigns.

Fix Technical Authentication Issues

Technical authentication forms the foundation of reliable email delivery. SPF, DKIM, and DMARC protocols work together to confirm your sending identity and protect against email spoofing.

Set up SPF records

SPF authentication needs adding a TXT record to your domain's DNS settings. This record lists all authorized IP addresses and servers that can send emails on behalf of your domain. The simple SPF record syntax begins with "v=spf1" and includes your authorized sending sources.

Key components of a proper SPF configuration include:

• IP addresses of your sending servers
• Third-party email service providers
• Enforcement rules (-all for strict, ~all for lenient)
• Maximum of 10 DNS lookups per record

We confirmed the envelope sender (MAIL FROM) address against your authorized sources. This provides the original protection, but SPF alone cannot guarantee complete email authentication.

Configure DKIM

DKIM adds a digital signature to your outbound messages through cryptographic authentication. The protocol needs two keys: a private key for your email server and a public key published in your DNS records.

To optimize security, implement DKIM with these specifications:

• Use 2048-bit keys instead of 1024-bit
• Rotate cryptographic keys at least once or twice yearly
• Add two signatures with different selectors for sensitive emails

In fact, DKIM verification helps receiving servers check if message content remains unchanged during transit. Notwithstanding that, DKIM must line up with your visible "From" address to pass DMARC authentication.

Implement DMARC

DMARC builds upon SPF and DKIM by ensuring domain alignment and providing reporting mechanisms. The protocol requires a TXT record that starts with "_dmarc" in your DNS configuration.

The DMARC policy tells receiving servers how to handle messages that fail authentication:

• p=none: Monitor mode without enforcement
• p=quarantine: Mark suspicious messages
• p=reject: Block failed authentications

Start with a monitoring policy (p=none) to receive reports about your email authentication status. As with other protocols, analyze these reports to identify legitimate sending sources and authentication failures before implementing stricter policies.

Messages pass DMARC when either SPF or DKIM authentication succeeds and lines up with the From address. This flexibility helps prevent false positives. Both SPF and DKIM provide the strongest protection against email spoofing.

Clean Up Your Email List

A clean email list is the life-blood of successful email deliverability. Your authentication protocols might be perfect, but sending to invalid or unengaged addresses will wreck your email strategy.

Remove invalid addresses

Your sender reputation needs protection through quick removal of invalid email addresses. Email lists decay at 25-30% annually. Regular cleaning plays a vital role in keeping your deliverability strong.

You need to remove invalid addresses because they:

• Damage your sender reputation
• Risk hitting spam traps
• Drive up campaign costs
• Hurt your engagement metrics

Start by adding email verification tools to spot addresses that bounce repeatedly. Double opt-in methods help new subscribers avoid typos and invalid entries. Regular database audits keep your list quality high.

Handle bounced emails

The way you handle bounces directly affects your sender reputation. Your bounce rates must stay below 2% to maintain healthy email deliverability.

Bounces come in two main types that need different handling:

1. Hard bounces: Permanent delivery failures that need immediate removal
2. Soft bounces: Temporary issues like full inboxes or server timeouts that need watching

Hard bounces need quick action - remove these addresses right away. Soft bounces need a gentler touch, with several delivery attempts before you remove them.

Update inactive subscribers

Mailbox providers track engagement levels, and inactive subscribers can hurt your deliverability. Smart management of these subscribers helps maintain healthy delivery rates.

Watch these engagement timeframes:

• 3-6 months: Time to send first warning
• 6-12 months: Critical point where action is needed
• 12+ months: High risk these could become spam traps

Launch a re-engagement campaign before removing subscribers. This costs five times less than finding new subscribers. Your re-engagement plan should:

1. Group inactive subscribers by engagement levels
2. Create messages that speak to each group
3. Let subscribers easily update their priorities
4. Remove contacts who don't respond

A smaller, engaged list works better than a large list of uninterested subscribers. Your email deliverability rates will improve naturally with good list hygiene, smart bounce management, and effective re-engagement campaigns.

Improve Sender Reputation

Sender reputation is the life-blood of successful email delivery that determines how Internet Service Providers (ISPs) review and route your messages. Your sender reputation works like a credit score and influences whether your emails reach the inbox or land in spam folders.

Monitor blacklist status

Your deliverability rates and sender reputation can suffer severe damage if you land on an email blacklist. The industry standard states that acceptable spam complaint rates should stay below 0.1%, or 1 in every 1,000 emails. We tracked suspicious behavior through three main categories:

• Email-based blacklists
• Server blacklists
• DNS blacklists (DNSBL)

These problems are systemic, so a resilient monitoring system is vital. Automated tools can notify you immediately when your IP or domain gets flagged. You should break down any sudden changes in these key indicators:

• Unexpected increases in email bounces
• Sharp decreases in open rates
• Spam complaints exceeding the 0.1% threshold

Regular monitoring and proper email authentication (SPF, DKIM, DMARC) demonstrate your steadfast dedication to spam prevention. Legitimate senders can still find themselves on blacklists occasionally.

Build consistent sending patterns

Your sending volume and patterns face close monitoring from ISPs that view sudden spikes as potential spam behavior. A steady cadence is everything in maintaining a positive reputation.

Different industries show varying optimal sending times to maximize participation:

IndustryBest DayBest TimeEcommerceWednesday10:00 AMSoftware/SaaSWednesday2:00 – 3:00 PMMarketing ServicesWednesday4:00 PMProfessional Services (B2B)Tuesday8:00 – 10:00 AMNGOs (Nonprofits)Tuesday/Wednesday3:00 – 4:00 PM

Consistent sending volumes help prove your legitimacy to ISPs. A dedicated IP gives you complete control over your sender reputation. This approach allows you to:

• Better monitor reputation metrics
• Identify potential issues faster
• Track engagement rates accurately

New domains or IPs should gradually increase sending volumes while monitoring subscriber engagement. This "warming up" process builds trust with ISPs and prevents reputation damage from sudden volume spikes.

Note that mailbox providers like Gmail and Outlook use sophisticated algorithms to assess your reputation. Services like Google Postmaster Tools, Microsoft SNDS, and Yahoo Sender Hub give an explanation about your sending practices so you can make needed adjustments.

Create Engagement-Focused Content

Compelling email content is the foundation of successful deliverability. Personalized emails get 26% higher open rates than generic messages. This makes content that encourages participation essential to land in the inbox.

Write clear subject lines

Your subject line creates the first impression in crowded inboxes. Subject lines under 5 words work best, and 3-letter subject lines get the highest participation rates.

These elements make subject lines work better:

• Create genuine value without over-promising
• Stay clear and specific
• Skip excessive capitalization or punctuation
• Add personal touches when it fits

Subject lines must match email content to avoid spam flags. Emails with personalized subject lines are 50% more likely to be opened. This shows how much tailored messaging matters.

Personalize email content

Personalized email content substantially boosts participation. About 74% of marketers see better customer participation through targeted personalization.

These personalization strategies work well:

1. Dynamic Content: Change content based on subscriber data and behavior
2. Segmentation: Group subscribers by priorities and participation levels
3. Behavioral Triggers: Send emails based on specific user actions
4. Geographic Customization: Match content to local priorities and time zones

Start by collecting first-party data to power these personalization efforts. Good segmentation helps you deliver messages that appeal to individual recipients.

Add value to recipients

Providing genuine value is vital to keep subscribers interested. Research shows people open emails that give them direct benefits.

Value-adding approaches that work best include:

Content TypeEngagement ImpactCase StudiesHigh credibilitySuccess StoriesStrong social proofCustomer TestimonialsPowerful conversion toolEducational ContentBuilds trustExclusive DealsDrives action

Helping customers solve problems works really well. Industry data shows relevant content that answers specific questions or challenges gets more people to participate.

Your content should:

• Show you understand customer needs deeply
• Give practical solutions to common challenges
• Share educational resources and insights
• Give exclusive value through special offers

Delivering valuable content consistently makes your brand a trusted resource instead of just another sender. Subscribers look forward to your communications when you take this approach.

Note that real participation comes from meeting subscriber needs, not promoting products. Customer-focused content naturally improves deliverability and builds stronger relationships with your audience.

Conclusion

Your email deliverability success relies on several connected factors that work together. Authentication protocols help protect your sending reputation. Clean email lists make sure your messages reach active and interested subscribers.

ISPs trust senders who maintain consistent patterns. Your reputation ends up depending on how well you deliver valuable, individual-specific content that connects with recipients. Your bounce rates should stay below 2%. Spam complaints need to remain under 0.1% to achieve the best deliverability.

This complete checklist helps protect your email deliverability in 2025 and beyond. You should start with proper authentication and then work on list hygiene and content that drives engagement. Your emails will land in subscribers' primary inboxes when you monitor performance metrics and make regular adjustments.