Safe email testing with Isolated Inbox

Test emails safely, with 5-minute setup, zero maintenance, and no risk of spamming recipients' inboxes

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Free plan available • ✓ No credit card required • ✓ 5-minute setup

Why  Isolated Inbox for testing?

Without isolated testing, you risk sending test emails to real customers with broken layouts, wrong content, or embarrassing mistakes. One accidental production email can damage your reputation. Isolated inboxes give you a safe sandbox to test freely.

Safe testing,
beautiful previews

With InboxSim, catch mistakes before they reach customers. Preview every detail.

Zero production accidents

All test emails captured safely in isolated inboxes. Never email real users by mistake.

Preview every detail

View HTML, plain text, and mobile versions. See exactly how emails render across devices.

All test emails safely captured in isolated inbox

Never email real users by mistake. All test emails are safely captured in isolated inboxes.

Team collaboration and member management

Share with stakeholders. Invite team members with different roles—no code access needed.

Collaborate
& ensure quality

Share with stakeholders. Verify deliverability.

Stakeholder sign-off

Share inboxes with non-technical team members. No code access needed.

Check spam scores

Ensure emails land in inboxes, not spam folders. Get actionable recommendations.

Built for
developers

Simple setup. Powerful search. Just works.

5-minute setup

Update your SMTP settings and start testing. No complex configuration.

Instant search

Find any email in seconds. Filter by sender, subject, or content.

Quick SMTP setup in minutes

Start testing in minutes. Copy your SMTP credentials and you're ready to go—no complex configuration.

Perfect for every team

Whether you're a solo developer or a large team, InboxSim adapts to your email testing needs.

Start Testing Today

Trusted by developers worldwide

Join teams who've eliminated production email accidents

100%
Production Safety
Zero accidental emails to real users
<5min
Quick Setup
From signup to first test email
24/7
Always Available
Test anytime, from anywhere

Play along with any framework

Simple SMTP configuration. No SDK required.

... and more
Start Testing Free

No credit card required • Start in minutes

Frequently Asked Questions

Find answers to common questions about InboxSim and how it can help you test emails effectively.

InboxSim is an email testing platform for developers and teams. It provides isolated inboxes for testing emails during development, with a beautiful UI for previewing emails and stakeholder-friendly views.

InboxSim offers flexible pricing with 4 tiers: Free ($0), Starter ($10/month), Team ($29/month - most popular), and Business ($59/month). All paid plans include a 14-day free trial with no credit card required. Save 10% with annual billing.

Yes! You can share your email inboxes with team members, stakeholders, or clients via secure links. Team members can view emails without accessing your code or infrastructure.

With our paid plan, you get unlimited email inboxes and unlimited email storage with 90-day retention. This gives you the flexibility to create separate inboxes for each project, environment, or team.

Simply point your application's SMTP configuration to InboxSim's SMTP server. All emails sent from your application will be safely captured in your isolated inbox instead of being delivered to real recipients.

Yes, we prioritize security. All emails are transmitted over secure connections and stored encrypted. Your test emails are isolated in your private inboxes and never sent to real recipients. We utilize industry-standard security practices to safeguard your data.