MailSandbox

MailSandbox

The email review layer for agencies.

MailSandbox is a fake SMTP sandbox that catches every email your staging environment tries to send, so nothing ever reaches a real recipient. Point any app at it — Laravel, Rails, Django, Node, or a raw socket — with just four lines in your .env, and every password reset, receipt, and digest is captured the instant it leaves, with the full HTML intact.

Built for the way agencies actually work, MailSandbox organizes captured emails by client and project, so you always know which message belongs where. Review the fully rendered HTML, catch deliverability issues early with built-in spam score analysis, and share a signed review link so clients can approve or comment without ever creating an account.

Main features

• Real fake SMTP — captures every message on a standard SMTP endpoint and stops it there; nothing is relayed to real recipients.
• Full HTML preview — see each email rendered exactly as it will land in an inbox, with the raw source one click away.
• Client + project structure — unlimited inboxes grouped by project, and projects grouped by client.
• Shareable review links — send a signed link; reviewers approve or comment with no account needed, and you can revoke it anytime.
• Spam score analysis — every captured email is scored so you catch deliverability issues before your client does.
• Whitelabel subdomains — serve review pages from your own domain with SSL, so clients see your studio, not ours.

Start capturing test emails in under sixty seconds — free, no credit card required.