Best Practices Tools to Test Transactional Email Deliverability By MailChannels | 4 minute read When it comes to transactional email, password resets, account alerts, order confirmations, deliverability is everything. If your messages don’t hit the inbox instantly, it’s not just an inconvenience; it’s a broken user experience. The good news? There are powerful tools available to help you test, monitor, and improve your transactional email deliverability before issues arise. In this blog, we’ll walk through the best tools (free and paid), what they’re good for, and how to use them effectively. Why You Should Test Deliverability (Yes, Even for Transactional Email) Transactional email isn’t promotional, but that doesn’t make it immune to spam filters or reputation issues. Here’s why regular testing matters: Authentication failures (SPF, DKIM, DMARC) can quietly erode trust New IPs or domains may be flagged until warmed up Content or formatting issues can trigger spam placement User complaints may not always be reported directly Deliverability testing tools help you identify potential problems early, validate infrastructure changes, and monitor inbox placement across providers like Gmail, Outlook, and Yahoo. Best Tools for Testing Transactional Email Deliverability Here’s a curated list of essential tools for testing and improving your email performance: 1. Mail-Tester https://www.mail-tester.com What it does: Mail-Tester provides a quick score (out of 10) based on your message’s SPF, DKIM, DMARC setup, spam score, and content. Use it for: Spot-checking new transactional templates Validating authentication records Getting instant spam filter feedback 2. Gmail Postmaster Tools https://postmaster.google.com What it does: Gives visibility into how Gmail evaluates your IP/domain, including spam rate, delivery errors, and authentication data. Use it for: Monitoring large-scale Gmail delivery Tracking domain reputation Confirming SPF/DKIM/DMARC health Note: You’ll need to verify domain ownership to access these insights. 3. MxToolbox Deliverability Tools https://mxtoolbox.com What it does: Offers a suite of tools including blacklist checks, SMTP diagnostics, DNS lookups, and header analysis. Use it for: Checking sender IP/domain blacklist status Performing SMTP or DNS lookups Analyzing message headers from bounced or spammed emails 4. MailReach https://mailreach.co What it does: Sends test emails to a network of real inboxes (Gmail, Outlook, etc.) and measures inbox placement over time. Use it for: Warming up new domains or IPs Monitoring real-world deliverability across providers Getting alerts when you start hitting spam 6. GlockApps https://glockapps.com What it does: Tests inbox placement by sending your message to dozens of seed inboxes across mailbox providers. Use it for: Visualizing inbox vs spam placement Testing impact of content changes Auditing deliverability for major ISPs 7. Litmus or Email on Acid (paid) https://www.litmus.com https://www.emailonacid.com What they do: Primarily for visual rendering, but they also include spam testing and deliverability checks. Use them for: Previewing how transactional emails look in 90+ clients Testing spam filters before launch Ensuring mobile and dark mode compatibility Pro Tip: Test Your Email Headers Too The message header is one of the most revealing parts of any email, and a common place where issues hide. → Learn how: How to Read an Email Header (with Real Examples) When and How Often Should You Test? Before launching a new transactional template When switching email providers or platforms After DNS/authentication updates (SPF, DKIM, DMARC) Monthly or quarterly, to monitor domain health Even minor changes, like a logo image or reply-to address, can affect deliverability. Routine testing helps catch these issues early. Related Resources SPF, DKIM, and DMARC for Transactional Email How to Monitor Email Performance (Delivery, Opens, Errors) What to Do When Users Don’t Receive Their Transactional Emails Diagnosing SMTP 5xx and 4xx Error Codes Make Deliverability One Less Thing to Worry About Testing is essential—but the best approach is to start with infrastructure built for deliverability. MailChannels Transactional Email includes smart diagnostics, automatic reputation management, and inbox-first delivery, so your transactional emails stay on track. Ready to stop worrying about email delivery? Get started with MailChannels Transactional Email today.