Top 10 Best Email Deliverability Tools to Improve Inbox Placement in 2026

 

Introduction

Sending an email is easy. Making sure it reaches the recipient’s inbox is a different challenge.

Businesses invest considerable time and money in email marketing, newsletters, customer notifications and sales campaigns. However, even a well-written message can fail to achieve its purpose if it ends up in a spam folder, gets rejected by the receiving server or never reaches the intended recipient.

This is why email deliverability has become an important part of modern digital marketing.

Email deliverability refers to the ability of an email to reach its intended destination, particularly the recipient’s inbox rather than the spam or junk folder. It depends on several factors, including sender reputation, domain authentication, email content, recipient engagement, list quality and sending practices.

Fortunately, businesses no longer need to manage every aspect of email delivery manually. Several specialised tools can help identify technical problems, monitor sender reputation, test email placement and improve the overall quality of marketing campaigns.

Whether you are managing a small newsletter, running an ecommerce business, operating a B2B sales department or sending thousands of promotional messages every month, the right email deliverability tools can make your campaigns more dependable.

In this guide, we explore 10 of the best email deliverability tools to consider in 2026, explaining their features, practical applications and the types of businesses that can benefit from them.

1. GlockApps – Email Inbox Placement Testing and Deliverability Monitoring

GlockApps is an email deliverability platform that helps businesses understand where their messages land after being sent. Rather than assuming that a successfully sent email has reached the inbox, marketers can use the platform to investigate whether messages arrive in the primary inbox, spam folder or another destination.

One of its most useful capabilities is inbox placement testing. Businesses can send test messages to a collection of test addresses across different email providers and examine the resulting placement reports.

GlockApps also provides spam testing, authentication analysis and reputation monitoring features. These capabilities help marketing teams identify potential delivery problems before launching important campaigns.

For example, an ecommerce business preparing a major promotional newsletter can test its message before sending it to thousands of subscribers. If the test identifies authentication problems or poor inbox placement, the marketing team can investigate and make corrections.

Key Features:

• Email inbox placement testing.

• Spam score and content analysis.

• SPF, DKIM and DMARC checks.

• Domain and IP reputation monitoring.

• Blacklist monitoring.

• Email deliverability reports.

Best For: Email marketing agencies, ecommerce businesses, newsletter publishers and organisations sending campaigns across multiple mailbox providers.

2. Google Postmaster Tools – Free Gmail Sender Reputation Monitoring

Google Postmaster Tools is one of the most useful free resources available to businesses that send emails to Gmail users. It provides information about how Google evaluates email traffic from a verified sending domain.

The platform helps senders monitor important signals such as domain reputation, IP reputation, spam complaint rates, authentication results and delivery errors.

These insights are valuable because Gmail uses several signals when deciding how to handle incoming messages. A business might have a technically valid email campaign but still experience delivery problems if its sending reputation deteriorates or recipients frequently report messages as spam.

Google Postmaster Tools helps identify these warning signs.

Another advantage is that the platform provides information directly from Google’s email ecosystem. This makes it particularly useful for businesses whose customers and subscribers primarily use Gmail.

However, it is important to understand that the platform does not test every email provider. Its information is focused on Gmail, and data availability can depend on sufficient sending volume.

Key Features:

• Gmail domain reputation monitoring.

• IP reputation information.

• Spam complaint rate reporting.

• SPF and DKIM authentication insights.

• DMARC-related compliance information.

• Delivery error monitoring.

Best For: Newsletter publishers, businesses sending bulk email, marketing agencies and organisations with substantial Gmail audiences.

3. MXToolbox – DNS, Blacklist and Email Authentication Monitoring

MXToolbox provides a collection of tools for diagnosing technical problems that can affect email delivery. It is particularly useful for businesses that want to examine their sending domains, DNS records, mail servers and blacklist status.

Email authentication is one of the most important areas covered by the platform. Incorrect SPF, DKIM or DMARC configurations can create problems when receiving servers attempt to establish whether an email genuinely comes from an authorised sender.

MXToolbox helps administrators examine these records and investigate possible configuration errors.

Its blacklist monitoring capabilities are also valuable. If a sending IP address or domain appears on a relevant blocklist, businesses can investigate the listing and determine whether corrective action is necessary.

For IT administrators and developers, MXToolbox provides practical diagnostic capabilities without requiring extensive email infrastructure expertise.

Key Features:

• SPF record analysis.

• DKIM and DMARC checks.

• DNS diagnostics.

• MX record lookup.

• IP and domain blacklist checks.

• Email infrastructure monitoring and alerts.

Best For: IT administrators, hosting companies, developers, email service providers and businesses managing their own sending infrastructure.

4. Mail-Tester – Simple Email Spam Testing

Mail-Tester is a straightforward tool for examining email messages before sending them to customers or subscribers.

Its basic approach is simple: users receive a temporary test email address, send their proposed message to that address and review the resulting report.

The report examines several aspects of the message, including authentication, spam-related characteristics, server configuration and other factors that may influence delivery.

This makes Mail-Tester particularly useful for marketers who want a quick assessment of their email campaigns without investing in a complicated deliverability platform.

For example, a newsletter publisher can test a newly designed email before scheduling a campaign. If the report identifies missing authentication records or potentially problematic message elements, those issues can be investigated before the actual distribution.

Mail-Tester is best viewed as a diagnostic tool rather than a guarantee of inbox placement. A good test result does not mean every recipient will receive the message in their primary inbox.

Key Features:

• Email spam testing.

• Spam-related content analysis.

• SPF and DKIM checks.

• Mail server configuration analysis.

• Message quality reporting.

• Pre-campaign testing.

Best For: Freelancers, small businesses, newsletter publishers and email marketers who need quick campaign checks.

5. EasyDMARC – Email Authentication and DMARC Management

EasyDMARC helps organisations manage email authentication and protect their domains against unauthorised email use.

Its primary focus is DMARC, an email authentication protocol that works alongside SPF and DKIM. These technologies help receiving email servers determine whether messages are authorised to use a particular domain.

DMARC also provides reporting capabilities that help domain owners understand which systems are sending messages using their domains and whether those messages pass authentication checks.

For businesses operating multiple email platforms, this information can be especially important. For instance, a company might use one service for newsletters, another for transactional notifications and a third for sales communications. Without proper authentication management, configuration mistakes can affect legitimate messages.

EasyDMARC helps organisations examine their authentication setup, review reports and work towards stronger domain protection.

Key Features:

• DMARC record monitoring.

• SPF and DKIM analysis.

• DMARC aggregate reporting.

• Domain authentication management.

• Email source identification.

• Authentication policy guidance.

Best For: Businesses managing multiple sending domains, IT departments, hosting providers and organisations concerned about email spoofing.

6. dmarcian – Detailed DMARC Reporting and Email Security

dmarcian is an email authentication platform that helps businesses understand and manage their DMARC implementation.

One of the challenges of DMARC is that its reports can be difficult to interpret without technical knowledge. These reports contain information about email sources, authentication results and sending infrastructure.

dmarcian makes this information easier to understand through reporting and analysis tools.

Businesses can use the platform to identify legitimate sending services, investigate unauthorised sources and understand whether their SPF and DKIM configurations are working correctly.

This is particularly useful for organisations that have several departments or third-party providers sending messages under the same corporate domain.

Rather than relying on occasional manual checks, administrators can use ongoing reporting to maintain better visibility into their email authentication environment.

Key Features:

• DMARC reporting and analysis.

• SPF configuration monitoring.

• DKIM authentication insights.

• Sending source identification.

• Domain authentication management.

• Support for DMARC policy implementation.

Best For: Medium-sized businesses, large organisations, IT security professionals and companies managing complex email infrastructure.

7. ZeroBounce – Email Verification and Deliverability Improvement

ZeroBounce is an email verification and deliverability platform that helps businesses maintain healthier contact databases.

Invalid email addresses are a common cause of unnecessary delivery failures. When organisations repeatedly send messages to addresses that do not exist, they risk damaging their sender reputation.

ZeroBounce helps reduce this problem by checking email addresses before campaigns are launched.

Its verification service identifies invalid, disposable, inactive and potentially risky addresses. It also provides tools that support email activity monitoring and deliverability analysis.

Another advantage is its API, which allows developers to incorporate email verification into websites, registration forms and customer acquisition applications.

For example, an online business can verify an email address when a visitor subscribes to its newsletter. This helps prevent incorrect or unsuitable addresses from entering the mailing database in the first place.

Key Features:

• Bulk email verification.

• Real-time email verification API.

• Disposable address detection.

• Spam trap and abuse-related address detection.

• Email activity data.

• Deliverability monitoring capabilities.

Best For: Ecommerce businesses, B2B marketers, newsletter publishers, lead generation agencies and companies managing large email databases.

8. Validity Everest – Enterprise Email Deliverability and Reputation Management

Validity Everest is an email deliverability platform designed to support organisations with sophisticated email marketing operations.

Large businesses often manage several campaigns, brands, sending domains and subscriber databases. Monitoring all these activities manually can become difficult, particularly when email performance differs across providers.

Everest provides tools for examining inbox placement, sender reputation and campaign performance. Its reporting capabilities help marketing teams understand how their messages perform across different email environments.

The platform also supports email testing and monitoring activities that can help identify problems before they affect large campaigns.

For businesses that depend heavily on email as a customer acquisition and retention channel, these insights can support more informed marketing decisions.

Its enterprise-oriented approach makes it particularly relevant to organisations that require broader deliverability management rather than occasional spam checks.

Key Features:

• Inbox placement monitoring.

• Sender reputation insights.

• Email campaign testing.

• Deliverability reporting.

• Email list and engagement analysis.

• Enterprise email marketing support.

Best For: Large ecommerce companies, financial services organisations, enterprise marketing departments and high-volume email senders.

9. Mailtrap – Email Testing and Transactional Email Delivery

Mailtrap is an email platform that helps developers and businesses test, inspect and manage application-generated emails.

It is particularly useful for software companies, SaaS businesses and developers building applications that send transactional messages.

Transactional emails include password reset notifications, account verification messages, purchase confirmations, payment receipts and other important communications.

During development, sending test messages to real customers can create unnecessary confusion. Mailtrap’s Email Sandbox provides a controlled environment where developers can capture and inspect outgoing messages without delivering them to actual recipients.

For production environments, Mailtrap also provides email sending infrastructure through its Email API and related services.

Its combination of testing and sending capabilities makes it a practical option for technology companies that want better control over application email workflows.

Key Features:

• Email testing sandbox.

• Transactional email sending.

• Email API integration.

• Message inspection and debugging.

• Delivery logs and analytics.

• Authentication and configuration support.

Best For: SaaS companies, software developers, ecommerce platforms, startups and businesses sending automated transactional emails.

10. Microsoft SNDS – Outlook and Hotmail Sender Reputation Monitoring

Microsoft Smart Network Data Services, commonly known as SNDS, is a free service that helps eligible email senders monitor the reputation and performance of their sending IP addresses within Microsoft’s Outlook.com email ecosystem.

For businesses that send substantial volumes of email to Outlook.com, Hotmail and related consumer mailboxes, understanding how Microsoft evaluates their sending infrastructure is important.

SNDS provides information about sending IP activity and reputation-related signals. It can help identify potential problems involving spam complaints, message traffic and sending behaviour.

Microsoft also provides a Junk Email Reporting Program, which gives participating senders additional feedback about messages that recipients report as junk.

These resources can help administrators investigate delivery problems and make better decisions about their sending practices.

SNDS is not a universal email deliverability checker, however. It focuses on Microsoft’s email environment and requires appropriate access to the sending IP information.

Key Features:

• Sending IP reputation information.

• Outlook.com delivery insights.

• Spam complaint-related reporting.

• Sending traffic monitoring.

• Access to additional Microsoft sender resources.

• Free reputation monitoring.

Best For: High-volume email senders, email service providers, hosting companies and businesses with significant Outlook and Hotmail audiences.

How to Choose the Best Email Deliverability Tool

Choosing an email deliverability platform requires understanding the problems affecting your campaigns. Not every tool performs the same function, and purchasing several overlapping services may create unnecessary expenses.

Consider the following factors before making a decision.

1. Inbox Placement Testing

Inbox placement testing helps determine where your messages are likely to arrive across different email providers.

A platform offering seed-list testing can show whether test messages reach inboxes, spam folders or other destinations. This is particularly valuable when campaigns experience inconsistent results across Gmail, Outlook, Yahoo and other providers.

GlockApps and Validity Everest are worth examining for this purpose.

2. Email Authentication

Authentication is essential for establishing trust between sending domains and receiving email servers.

Three important technologies are:

• SPF: Specifies which servers are authorised to send email for a domain.

• DKIM: Uses cryptographic signatures to help verify that a message is associated with an authorised sending domain and has not been altered in transit.

• DMARC: Provides policy and reporting mechanisms that build on SPF and DKIM authentication.

EasyDMARC and dmarcian are useful options for organisations that need dedicated authentication management.

3. Sender Reputation Monitoring

Sender reputation can influence how mailbox providers handle incoming messages.

A domain or IP address with poor sending history may experience increased filtering, rejection or spam-folder placement.

Google Postmaster Tools and Microsoft SNDS provide valuable information about how their respective email ecosystems view sending activity.

4. Email List Verification

A mailing list containing invalid or risky addresses can undermine an otherwise well-managed email campaign.

Email verification tools help identify problematic contacts before sending messages.

ZeroBounce is an option for businesses that want to combine contact verification with broader deliverability-related services.

5. Spam Testing and Content Analysis

Email content can influence how receiving systems evaluate messages. Suspicious links, misleading subject lines, poorly configured HTML and other characteristics may contribute to filtering.

Tools such as Mail-Tester can help identify potential problems before campaigns are distributed.

6. API and Automation Support

Businesses that collect customer information through websites and applications should consider tools with API support.

Automated verification and authentication monitoring can reduce manual work and make it easier to maintain consistent email quality.

This is particularly useful for ecommerce stores, SaaS platforms, subscription services and large online communities.

Best Email Deliverability Tools by Business Need

Here is a practical way to narrow down the selection:

• Best for inbox placement testing: GlockApps.

• Best free Gmail monitoring: Google Postmaster Tools.

• Best for DNS and blacklist checks: MXToolbox.

• Best for quick spam testing: Mail-Tester.

• Best for DMARC management: EasyDMARC.

• Best for detailed DMARC reporting: dmarcian.

• Best for email verification: ZeroBounce.

• Best for enterprise deliverability: Validity Everest.

• Best for transactional email testing: Mailtrap.

• Best free Outlook reputation monitoring: Microsoft SNDS.

These are use-case recommendations rather than results of a single comparative performance test.

Practical Ways to Improve Email Deliverability

Even the best email deliverability software cannot compensate for poor email marketing practices. Businesses should combine technical monitoring with responsible sending habits.

Authenticate your sending domain. Configure SPF, DKIM and DMARC correctly. Make sure the configuration covers all legitimate services sending messages on behalf of your domain.

Maintain a clean email database. Remove invalid addresses, respect unsubscribe requests and avoid purchasing questionable contact lists.

Send relevant messages. Segment subscribers according to their interests, preferences and previous interactions. Relevant messages are more likely to generate positive engagement.

Monitor spam complaints. A growing number of complaints can indicate that subscribers do not recognise, want or expect your messages.

Increase sending volume gradually when appropriate. New domains and IP addresses should establish a consistent sending history rather than immediately generating unusually large volumes of email.

Use proper unsubscribe mechanisms. Marketing emails should make it straightforward for recipients to stop receiving unwanted messages. Applicable mailbox-provider requirements, including one-click unsubscribe for qualifying bulk marketing messages, should be followed.

Monitor delivery performance regularly. Review bounce rates, authentication results, complaint rates, domain reputation and inbox placement trends. Investigate sudden changes rather than assuming every campaign will perform equally.

Case Studies: How Businesses Can Use Email Deliverability Tools

The following are illustrative business scenarios showing how different organisations could apply these tools. They are not independently verified customer case studies.

Case Study 1: An Ecommerce Store Reduces Email Delivery Problems

An online clothing retailer has a database of approximately 80,000 subscribers. The business regularly sends product announcements, discount offers and seasonal promotional newsletters.

Over time, its marketing team notices that campaign engagement is becoming inconsistent. Some subscribers receive messages, while others report that promotional emails are appearing in spam folders.

The company decides to investigate its email infrastructure.

First, it uses ZeroBounce to review the quality of its mailing list. It then checks its sending domain with Google Postmaster Tools and uses GlockApps to examine inbox placement across different providers.

The investigation identifies several issues, including outdated contacts and authentication configuration problems.

After cleaning the database, correcting the authentication records and improving audience segmentation, the business establishes a more disciplined campaign process.

Business lesson: Email deliverability should be managed through a combination of list quality, authentication and ongoing monitoring.

Case Study 2: A SaaS Company Improves Transactional Email Reliability

A software company sends thousands of automated emails every day. These include account verification links, password reset instructions, subscription confirmations and billing notifications.

Some customers complain that important account-related messages are arriving late or cannot be found.

The development team uses Mailtrap to inspect application-generated messages and investigate delivery logs. It also reviews its authentication configuration and examines the sending domain using MXToolbox.

The company discovers inconsistencies in its email configuration and makes the necessary corrections.

It subsequently introduces regular testing whenever changes are made to its application email system.

Business lesson: Transactional email deserves the same technical attention as marketing email because failed notifications can affect customer satisfaction and business operations.

Case Study 3: A B2B Marketing Agency Strengthens Its Email Campaigns

A digital marketing agency manages campaigns for several business clients. Each client has different audiences, sending domains and marketing objectives.

The agency struggles to maintain consistent deliverability because some clients have properly configured authentication while others have neglected their domain settings.

The agency adopts EasyDMARC for authentication management and uses Mail-Tester for pre-campaign checks.

For clients sending substantial volumes to Gmail, it also uses Google Postmaster Tools to monitor reputation and spam complaint signals.

The agency introduces a standard email delivery checklist before approving campaigns.

Business lesson: Agencies managing several client accounts benefit from standardised deliverability procedures and regular technical checks.

Case Study 4: A Newsletter Publisher Protects Its Sender Reputation

An independent publisher has built a newsletter with more than 35,000 subscribers. Its mailing list has grown steadily through website registrations and promotional partnerships.

However, the publisher rarely checks inactive addresses or investigates delivery problems.

After reviewing its email performance, the publisher introduces regular list verification and uses Gmail reputation monitoring to understand how its messages are being received.

It also improves its subscription process to ensure that new contacts genuinely want to receive the newsletter.

Over time, the publisher develops a more sustainable email management routine.

Business lesson: A large subscriber database is only valuable when it contains relevant contacts who genuinely want to receive communications.

Frequently Asked Questions About Email Deliverability Tools

1. What is an email deliverability tool?

An email deliverability tool is software that helps businesses monitor, test and improve the likelihood that their messages reach recipients’ inboxes. Depending on the platform, it may provide spam testing, inbox placement analysis, sender reputation monitoring, email authentication checks or contact verification.

2. Which is the best email deliverability tool?

GlockApps is a strong option for inbox placement testing, while Google Postmaster Tools is particularly useful for free Gmail reputation monitoring. MXToolbox is valuable for technical diagnostics, and Validity Everest is designed for more extensive enterprise requirements.

3. Are there free email deliverability tools?

Yes. Google Postmaster Tools, Microsoft SNDS, MXToolbox’s basic diagnostic tools and Mail-Tester offer free capabilities. Their features and usage limitations differ.

4. Can email deliverability tools prevent emails from going to spam?

They can help identify and correct problems that contribute to spam filtering, but no tool can guarantee inbox placement. Receiving providers make their own filtering decisions based on authentication, reputation, content, recipient behaviour and other signals.

5. What is the difference between email verification and email deliverability?

Email verification examines whether an email address appears valid and suitable for sending. Email deliverability concerns whether a message successfully reaches its intended destination, particularly the inbox. Both are important, but they solve different problems.

6. How often should businesses test email deliverability?

Businesses should monitor important deliverability indicators continuously where possible and conduct additional tests before major campaigns, after infrastructure changes and whenever delivery performance deteriorates.

7. Do SPF, DKIM and DMARC improve email deliverability?

Yes. Properly configured authentication helps receiving servers verify legitimate sending activity and protects domains against certain forms of spoofing. These protocols are important components of a healthy email delivery setup.

8. Can a business use multiple email deliverability tools?

Absolutely. In fact, combining complementary tools can provide better coverage. For example, a business might use Google Postmaster Tools for Gmail reputation, MXToolbox for DNS monitoring and GlockApps for inbox placement testing.

Conclusion

Email deliverability is an important part of building a successful email marketing operation. Businesses can spend considerable resources creating attractive newsletters, personalised campaigns and automated customer messages, but those investments are less valuable when emails fail to reach their intended recipients.

The 10 tools covered in this guide provide different ways to address email delivery challenges. GlockApps helps businesses examine inbox placement, Google Postmaster Tools provides Gmail-specific reputation insights, MXToolbox supports technical diagnostics, and EasyDMARC and dmarcian help manage email authentication.

Meanwhile, ZeroBounce supports contact database quality, Validity Everest serves more advanced marketing operations, and Mailtrap helps developers test and manage transactional email workflows.

The most effective approach is not necessarily to purchase every available tool. Instead, identify the weaknesses in your current email infrastructure and select software that addresses those specific problems.

Start with domain authentication, maintain a clean subscriber database, monitor sender reputation and test important campaigns before sending them.

With the right combination of technology and responsible email practices, businesses can build more reliable communication systems, protect their sending reputation and make better use of their email marketing investments.