mailpit-integration

Use Mailpit, a lightweight SMTP server that captures all outgoing emails without delivering them. Add it as a container in your .NET Aspire AppHost, point your app's SMTP settings at it, and view captured messages in its web UI on port 8025.

Create a MailpitClient that calls the Mailpit HTTP API endpoints like /api/v1/messages. In your test fixture, start the Aspire app, clear messages, trigger the workflow, then assert on captured subjects, recipients, and HTML bodies.

MailKit is the recommended library for SMTP in modern .NET. It supports async sending, authentication, and SSL options, and works with Mailpit in development by connecting without SSL or credentials on port 1025.

Yes. When you add Mailpit as a container resource with named endpoints in the AppHost, its web UI endpoint appears in the Aspire dashboard under Resources, giving one-click access to the captured email inbox.

First confirm the Mailpit container is running in the Aspire dashboard, then verify your app's SMTP host and port configuration matches the container endpoint. Check application logs for connection exceptions and test the API with curl on port 8025.

Poll the Mailpit API with a WaitForMessageAsync helper that retries with a short delay until a matching message arrives or a timeout expires. This handles emails sent by background jobs or event handlers after the HTTP response completes.