Safe capture
No accidental sends
Route non-production SMTP traffic into controlled inboxes instead of real customer mailboxes.
Capture and verify test email safely before production
MailSlurp Email Sandbox captures SMTP traffic from dev, staging, and QA so teams can inspect messages and automate checks. Replace manual inbox review and flaky timing heuristics with deterministic inbox APIs built for CI.
Deterministic waits
CI-ready checks
Wait for matching emails, extract links/codes, and fail fast on timeouts and regressions.
Isolated inboxes
Parallel builds
Provision inboxes per worker or per run so messages never collide across CI pipelines.
Deep inspection
Actionable debugging
Inspect headers, HTML/text, attachments, and metadata to diagnose failures quickly.
Core capabilities
What teams need when email workflows matter
Connect any SMTP-capable app in minutes
Point your application at sandbox credentials and start capturing test traffic immediately, without changing your workflow.
- SMTP capture
- Staging
- QA
Automate release gates with wait and assertion APIs
Block until the right email arrives, then assert on subject, sender, links, tokens, headers, and attachments.
- Wait for email
- Extract links
- Assertions
Validate content quality and compatibility signals
Catch broken links, missing images, and risky template changes before they ship to customers.
- Links
- Images
- Compatibility
Scale with controls and automation when you are ready
Adopt one platform for inbox capture, test automation, webhooks, and operational workflows with audit-ready controls.
- Webhooks
- Governance
- Scale
Team use cases
How engineering, QA, and operations teams use MailSlurp
QA + release engineering
Email checks as a release gate
Gate releases on the inbox flows that protect onboarding, auth, and billing reliability.
- Reduce flaky test failures from shared mailboxes
- Catch broken links, codes, and templates early
- Make failures reproducible with full payload inspection
Product engineering
Staging validation for critical journeys
Validate sign-up, reset, invites, and notifications in staging with isolated inboxes and deterministic waits.
- Keep staging behavior realistic and testable
- Debug regressions with message metadata and headers
- Standardize inbox patterns across services
Platform teams
Standard inbox infrastructure for the org
Provide shared inbox primitives for dev, staging, and CI so teams ship consistent messaging workflows.
- Reduce mailbox tooling sprawl
- Improve ownership and auditability for messaging checks
- Make onboarding faster for new services and teams
Getting started
Get this working quickly, then build on it
Day 1
Capture one workflow safely
Route a single non-production workflow to a sandbox inbox so your team can inspect messages and define checks.
- Connect your app to sandbox SMTP capture
- Trigger the workflow (sign-up, reset, invite)
- Inspect the message payload and identify assertions to automate
Week 1
Automate checks in CI
Add deterministic waits and payload assertions so regressions fail builds automatically.
- Create an inbox per run or per worker
- Wait for the matching email with explicit timeouts
- Assert on links, codes, headers, and required content
Week 2+
Expand to compatibility and deliverability checks
Scale coverage to templates that impact revenue and customer trust.
- Add link and image checks for key templates
- Run compatibility checks for high-impact clients
- Add deliverability diagnostics where required
Team fit
How different teams get value
QA and SDET teams
Challenge: Manual inbox review and timing heuristics make CI suites slow and unreliable.
What improves: Run deterministic email checks with isolated inboxes per test run.
Engineering managers
Challenge: Email regressions ship when release gates are weak or inconsistent across teams.
What improves: Adopt repeatable inbox assertions as a standard release control.
Platform and DevEx teams
Challenge: Multiple tools exist for fake SMTP, inboxes, and QA, but ownership is unclear.
What improves: Centralize inbox capture and automation primitives in one platform.
Customer outcomes
What gets better once MailSlurp is in place
Safer staging and QA
Capture non-production traffic in controlled inboxes to avoid accidental sends and messy mailbox sprawl.
More reliable automation
Deterministic waits and isolation reduce flaky failures and increase confidence in release gates.
Faster debugging
Inspect the full payload (headers, HTML, attachments) to fix regressions quickly.
Clear upgrade path
Start with one workflow, then expand coverage and add team controls as your team scales.
Ready to try this with your own workflow?
FAQ
Questions people ask before they start
Can we use this with any app that sends SMTP?
Yes. Connect any SMTP-capable application to capture email in sandbox inboxes and automate checks with APIs.
Does this work in parallel CI?
Yes. Provision inboxes per worker or per run so messages never collide across parallel builds.
Can we validate links, codes, and attachments?
Yes. Wait for matching emails and assert on extracted links/codes, headers, HTML/text, and attachments.
Do we need to migrate everything at once?
No. Start with one high-impact workflow, then expand to more templates and environments as you see reliability gains.