Agent skill · software engineering · aaronontheweb
mailpit-integration
Test email sending locally using Mailpit with .NET Aspire. Captures all outgoing emails without sending them. View rendered HTML, inspect headers, and verify delivery in integration tests.
Why this skill is useful
Adds specific Mailpit integration patterns and configuration examples for .NET Aspire that the AI wouldn't reliably generate on its own.
What it needs
Requires docker installed locally. About 5k tokens when loaded. Last updated 2026-07-03. 1,095 stars on the source repository.
What this skill does
Email Testing with Mailpit and .NET Aspire When to Use This Skill Use this skill when: Testing email delivery locally without sending real emails Setting up email infrastructure in .NET Aspire Writing integration tests that verify emails are sent Debugging email rendering and headers Related skills: aspnetcore/mjml-email-templates - MJML template authoring testing/verify-email-snapshots - Snapshot test rendered HTML aspire/integration-testing - General Aspire testing patterns --- What is Mailpit? Mailpit is a lightweight email testing tool that: Captures all SMTP traffic without delivering emails Provides a web UI to view captured emails Exposes an API for programmatic access Supports HTML rendering, headers, and attachments Perfect for development and integration testing. --- Aspire AppHost Configuration Add Mailpit as a container in your AppHost: --- SMTP Configuration appsettings.json Configuration Class Service Registration --- Email Sender Implementation Requires MailKit package: --- Viewing Captured Emails Web UI Navigate to http://localhost:8025 to see: Inbox - All captured emails HTML view - Rendered email Source view - Raw HTML/MJML output Headers - Full email headers Attachments - Any attached files Aspire Dashboard The Mailpit UI endpoint appears in the Aspire dashboard under Resources. --- Integration Testing Test Fixture with Aspire Mailpit API Client --- Aspire Test Fixture --- Common Test Patterns Wait for Async Email Some emails are sent asynchronously. Wait for them: Verify Multiple Emails Verify Email Content --- Production vs Development --- Troubleshooting Emails Not Appearing 1. Check Mailpit container is running in Aspire dashboard 2. Verify SMTP host/port configuration 3. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills aaronontheweb/aspire-mailpit-integration