The Best GlockApps Alternatives for Email Testing and Deliverability

Last Updated on March 31, 2025 by Ewen Finser

If you’re trying to make the most out of your emails before they even go out, then you’ve probably heard of GlockApps. It’s a solid tool, but it’s not the only one out there.

Maybe you need better deliverability insights, more automation, or something that fits your budget better.

Or maybe GlockApps just isn’t cutting it for your specific needs, and you’re on the hunt for an alternative that works better. Whatever the case, the good news is that there are plenty of great options to choose from.

The right email testing tool can make a huge difference in how your emails perform. It doesn’t matter if you’re running a business, working in development, or managing email campaigns, you want a tool that not only catches errors but also helps your emails land in the inbox where they belong.

Let’s take a closer look at the best GlockApps alternatives and what makes each one worth considering.

Why Choosing the Right Email Marketing Tool Matters

Getting your emails into inboxes isn’t as simple as hitting “send.” Even if you craft the perfect message, it might land in the spam folder or not get delivered at all. That’s why having the right email testing and deliverability tool is essential. It helps you catch issues before they happen, so your emails actually reach your audience.

Make Sure Your Emails Land in the Inbox

Imagine spending hours writing a great email, only to find out most of your recipients never saw it because it went straight to spam. A good deliverability tool checks for common spam triggers, like flagged words, broken links, or missing authentication. It gives you a deliverability score and suggestions to improve your chances of hitting the inbox.

Test How Your Email Looks Before Sending

Ever opened an email on your phone and seen broken images or weird formatting? Different email providers (Gmail, Outlook, Yahoo) display emails differently, which can mess up your design. A testing tool previews how your email will look across devices and inboxes, so you can fix any issues before sending.

Protect Your Sender Reputation

If too many of your emails bounce or get marked as spam, email providers start flagging you as an untrustworthy sender. This can affect all your future emails, even the important ones. Deliverability tools track your sender reputation and help you follow best practices, like setting up SPF, DKIM, and DMARC authentication. Think of it as email hygiene, keeping your sender status clean so your messages don’t get blocked.

Get Data on What’s Working (and What’s Not)

A good email testing tool doesn’t just catch mistakes, it also shows you how well your emails perform. You’ll get insights into open rates, click-through rates, and spam complaints. If people aren’t opening your emails, maybe your subject line needs work. If they’re clicking but not converting, your content might need tweaking. Testing helps you make data-driven improvements instead of guessing.

The Best GlockApps Alternatives

Now you already know why you need the best email testing and deliverability tool, so there’s one thing left to do: find it. These are the main GlockApps alternatives you should be looking at if you don’t want to be disappointed: 

InboxAlly – Best for Improving Email Deliverability

If your biggest worry is making sure emails land in inboxes instead of spam folders, InboxAlly is a strong choice. Unlike GlockApps, which focuses on testing, InboxAlly actively improves your sender reputation to help you improve your deliverability rates. That means fewer bounced emails and more messages reaching the people who need to see them.

Key Features:

• Email warmup: Gradually builds a positive sending reputation by increasing engagement with your emails over time.
• Spam avoidance: Uses smart techniques to keep your emails from getting flagged, so you don’t end up in the junk folder.
• Inbox placement Tracking: Shows you exactly where your emails are landing (Primary, Promotions, or Spam) so you can make adjustments.
• Automation and AI Optimization: Learns from past performance and helps improve future campaigns automatically.

Who Shouldn’t Use InboxAlly?

If you just need an easy way to test emails in a safe environment, InboxAlly might be more than you need. This tool is for those who would rather work on improving deliverability rather than simple email testing to get things somewhat figured out.

MailHog – Best Open-Source GlockApps Alternative

If you’re a developer looking for a free, no-frills email testing tool, MailHog is a fantastic option. It’s simple, lightweight, and perfect for local testing, which makes it a great pick for those who just need a straightforward way to capture test emails without any extra bells and whistles.

Key Features:

• Completely free and open source: No subscription fees, making it ideal for budget-conscious devs.
• SMTP capture: Catches outgoing emails so you can test without sending them to real users.
• Web interface: Lets you view and inspect test emails in a browser, simulating how they’ll appear in an inbox.
• Works with docker: Integrates easily into containerized environments for seamless development.

Who Shouldn’t Use MailHog?

MailHog is great for local testing but also lacks deeper insights. This means that if you need analytics, spam testing, or inbox placement tracking, MailHog is probably too basic for you. 

Mailosaur – Best for Advanced Email Testing

Mailosaur is a powerhouse when it comes to email testing. It’s built for QA teams and developers who need serious testing capabilities, making it perfect for catching issues before emails go live.

Key Features:

• Automated testing: Hooks into your CI/CD pipelines for continuous testing to make sure no broken emails slip through.
• Spam testing: Helps you detect if your emails are likely to get flagged before they even reach users.
• SMS testing: Lets you test SMS messages for multi-channel campaigns.
• Email analytics: Provides insights into test email performance so you can optimize for better engagement.

Who Shouldn’t Use Mailosaur?

Mailosaur is packed with features, but not everyone needs that level of depth. If you just need a simple tool to capture test emails, Mailosaur might be too much.

 SMTP2GO – Best for Reliable Email Sending

Need a tool that does more than testing? SMTP2GO is a full transactional email service with built-in deliverability features. If you’re looking for reliable email sending with real-time tracking, this is a solid pick.

Key Features:

• Reliable email sending: Makes sure your emails get delivered quickly and efficiently.
• Real-time analytics: Tracks email delivery, open rates, and engagement as they happen.
• Bounce and spam monitoring: Lets you know if there are any issues affecting deliverability so you can fix them before they become bigger problems.
• Global infrastructure: Reduces latency and speeds up delivery all over the world, which makes it great for international businesses.

Who Shouldn’t Use SMTP2GO?

If you just want a basic tool to capture test emails, SMTP2GO isn’t the right fit. It’s designed for actual email sending, not just testing.

Papercut SMTP – Best for Local Email Testing

If you’re a developer looking for an easy way to test emails locally, Papercut SMTP is a great option. It’s lightweight, simple to use, and doesn’t require an internet connection to function, making it perfect for testing in a local environment.

Key Features:

• It needs no configuration: Just install it and start capturing emails instantly.
• Works offline: No need for an external SMTP server, making local testing a breeze.
• User-friendly interface: View test emails easily with a simple web UI.
• Supports multiple platforms: It works on Windows, macOS, and Linux.

Who Shouldn’t Use Papercut SMTP?

If you need analytics, spam testing, or advanced automation, Papercut SMTP might be too basic. It’s designed for simple email capture and testing, not full deliverability tracking.

How to Choose the Best GlockApps Alternative

The best GlockApps alternative depends on what you need. If improving deliverability is your priority, InboxAlly is a strong contender. For local testing, MailHog and Papercut SMTP are great free options. If you need advanced testing features, Mailosaur is the way to go. And if you’re looking for a reliable sending service, SMTP2GO won’t disappoint.

At the end of the day, the right tool is the one that helps you get your emails exactly where they need to go, whether that’s inboxes, test environments, or both. Take the time to explore your options and choose the one that fits your workflow best.