MailSandbox

MailSandbox is an email testing service built for agencies and teams managing multiple clients and projects. Its fake SMTP sandbox captures messages sent from staging environments, preventing them from reaching real recipients while keeping their full content available for review. It works with standard SMTP clients and popular frameworks, including Laravel, Rails, Django, and Node, without requiring a proprietary SDK.

Users can organize unlimited inboxes by project and client, preview responsive HTML, inspect raw email source, and analyze spam scores to identify potential deliverability issues. Teams can share secure review links with clients, who can view specific messages without creating an account; links can be revoked or set to expire. MailSandbox also offers an MCP connection for Cursor and Claude, enabling developers to send and inspect test emails from their AI coding tools.

Plans range from a free option for personal testing to paid tiers with higher email volumes, more active projects, and features for agency collaboration and load testing.