Email testing is used to check for typos, formatting issues, inbox placement, layout faults, design defects, and other issues in emails and newsletters. Typically, the email or newsletter is finalized before publishing and distributing to the contact list.

Unfortunately, there is no one fix-all tool to check whether your email is ready to go. However, this article will provide a universal email testing checklist for developers to test email and which precise tool can assist them.

Testing of Email Sending Capability

There are two things you can test here, SMTP server capabilities and testing email sending.

SMTP server capabilities testing

For this, you can either test your mail server or do load testing.

Email Server Testing


  • HTTPS Secured Web Serving Testing
  • POP3 Mail Server Testing
  • Remote Ping


  • Email Analyzer
  • Inbox, spam, or promotions
  • Link checker


  • DNS Report
  • IP address information
  • Ping tool
  • DNSBL/URIBL spam database lookup

Load testing of SMTP server

Apache JMeter

  • Load testing functional behavior and performance measuring
  • Analyze overall performance
  • Tests TCP, FTP, SOAP/REST Webservices

MultiMail 2.0

  • Loads test mail server
  • Sends a large number of emails parallel to a specified SMTP server

Testing email sending

You can now use a third-party or dummy SMTP server to send test emails. These tests do not need the use of your mail server and allow you to examine your app's email sending functionality and test email delivery.

Sending test email via SMTP


  • Multi-part emails
  • Shows mail instantly

Email API testing


  • Webhooks testing
  • Split testing
  • Spam filter testing
  • Multiple templates per account


  • Automated end to end testing
  • Vast integration support
  • HTML test
  • Spam test


Unique email address per inbox


  • Unique email address per inbox

Shared inbox for the development team


  • Shared inbox for the team


  • Multiple temporary shareable inboxes
  • Super inbox

Load testing of your app email sending


  • Sending rate limits per 10 sec

Spam Testing

The next step would be to ensure that your email campaign won't be marked as spam.

Deliverability test


  • Marketing
  • Signup forms
  • Email heat map
  • A/B testing


  • Email parsing
  • Transactional emails
  • Email validation
  • Burst sending

Send forensics

  • Enterprise sender assurance
  • Live inbox placement testing
  • Deliverability alerts
  • DMARC Compliance verification

Email spam test

Mail tester

  • iFrame CSS and JSON API
  • Micro-payment mode
  • 18 languages support

Glock Apps

  • Reputation monitor
  • Developer API
  • Gmail tab tracking
  • Automated tests for outreach or transactional emails

  • Accessibility check
  • Email preview
  • Eye-tracking prediction heat map

Spam checker by Postmark

  • Postmark delivery status
  • Versatile email sending options

Email address validity test

The Checker

  • 99% validation accuracy
  • Powerful API
  • TXT, CVS, XLS, and XLS formats supported
  • Free email duplication removal


  • Real-time verification through API
  • High-risk email detection
  • Syntax verifier
  • Detectors: Temporary unavailability, catch-all, Rola Account


  • Flexible pricing options
  • Mail server validation
  • Domain health check
  • Custom API and Webhook

Test mail content

Client testing checks how an email looks at different devices, browsers, or email clients.

Email client testing or preview test


  • Spam testing
  • Litmus builder
  • Advanced security
  • Integrations with famous marketing tools

Email on Acid

  • HTML testing
  • URL validation
  • B2B/B2C spam filter testing
  • Heat mapping

Email preview services

  • 100% white-label API
  • Spam score testing
  • Delivery duration tracking
  • Email analytics

HTML test


  • CSS inliner
  • Test history

HTML Email Check

  • Accessibility validation
  • Layout viewer
  • Mobile validation
  • Developer checklist

Test body copy


  • Grammar checks
  • Punctuation checks
  • Sentence structure checks
  • Plagiarism detector

Hemingway Editor

  • Readability check
  • Counter of letters, characters, words, sentences, paragraphs
  • Reading time counter


  • Persona dashboard
  • API
  • Google Docs add-on

Email split testing or A/B testing


  • Custom-coded templates
  • Comparative reporting
  • Integrations with 200+ Apps
  • 24/7 Email and chat support

Campaign monitor

  • Hundreds of professional templates
  • Visual journey designer
  • Sign up forms
  • Vast analytical capabilities

Active campaign

  • HFree and fast migration option
  • Dynamic content
  • Subscription forms
  • Email segmentation

Subject line testing

Send Check It

  • Slack subject line tester
  • API

Subject Line

  • Evaluates subject line

Email subject line grader

  • Sets a score grade for your subject line
  • Explains what's wrong with it


Now that we have come to the end of our list of email testing tools, you have all you need to complete this task more swiftly and efficiently. Create an email testing checklist to follow these steps more effectively. Also, more tools are coming into the market, so don't be afraid to try them out