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Sink

Any stack MIT licensed

Every message staging would have sent, in an inbox you own. Laravel apps switch one mail driver, anything else posts the same JSON envelope, and nothing is ever delivered. Your team reads the mail in a sandboxed inbox; your agents assert on it over an MCP server that never sees a body.

Deploy Sink for free Or run it yourself, free Read the Docs
Replaces
Hosted email sandboxes
Runs on
Your Laravel Cloud account
Needs
Compute · Database · Queue · Object storage · Scheduler

What it captures

Metadata in Postgres, raw MIME and attachments in your bucket

  • Drop-in Laravel transport

    Install the client, set the mail driver to sink, and every send is captured. It retries with backoff and fails loudly rather than silently.

  • A production fuse

    The transport refuses to build in production unless you say so explicitly, so it cannot swallow real mail by accident.

  • Exact send counts

    Every send carries a client-minted idempotency key, so a retried send collapses and a genuine duplicate stays distinct.

  • Parsed, filterable metadata

    Subject, sender, every recipient and header, extracted links and attachment details, filterable by app, recipient, subject and date.

  • A sandboxed inbox

    Invitation-only, with HTML rendered in a locked-down frame plus raw source, headers, links and attachment downloads.

  • Retention you set

    Days, a message cap and a byte cap, pruned hourly, on your own storage.

  • Body-blind assertions

    MCP

    Ten tools give an agent apps, counts, recipients, headers, links and a yes-or-no on whether a body matches, never the body itself. The only write is a scoped purge that refuses to wipe everything.

  • One inbox, any number of apps

    Each token names the app that sends through it, and every filter in the UI and the MCP server can scope to one. Oversized mail degrades to headers-only rather than losing the send.

Sink vs. the incumbents

We rebuilt one row of their feature matrix

Mailtrap, Mailosaur and Mailpit are good tools, and Sink is not trying to replace them. It does one slice — capture outbound mail on infrastructure you own, and let humans and agents check it — and deliberately does not do the rest. The question is not which product is better. It is which slice you are actually using.

Sink feature comparison
Feature Sink Self-hosted, MIT Mailtrap Hosted Mailosaur Hosted Mailpit Free, you run it
Capture staging mail in an inbox your team reads the row we rebuilt Does this well:Yours, on your account Does this well:Included Does this well:Included Does this well:Included
Agent assertions that never read a body the row we rebuilt Does this well:MCP, body-blind Partly, or with a caveat:REST API, full access Partly, or with a caveat:SDKs, full access Partly, or with a caveat:REST API, full access
Plain SMTP capture from any language we did not build this Not built:HTTP ingest only Does this well:Any SMTP app Does this well:SMTP, POP3, IMAP Does this well:Built in
Spam scoring we did not build this Not built:By design Does this well:Built in Does this well:Built in Partly, or with a caveat:With SpamAssassin
Rendering checks across mail clients we did not build this Not built:Sandboxed render only Does this well:Client analysis Works, but on their terms:Paid add-on Partly, or with a caveat:Compatibility score
Forward or release real mail we did not build this Not built:Capture only Works, but on their terms:Quota per plan Does this well:Included Does this well:Relay config
Where your mail lives Does this well:Your Postgres and bucket Works, but on their terms:Their cluster Works, but on their terms:Their cluster Does this well:Your container
Cost of sending more test mail Does this well:Disk Works, but on their terms:Per message tier Works, but on their terms:Per message tier Does this well:Disk
Retention Does this well:Days and size caps, yours Works, but on their terms:Plan-tiered Works, but on their terms:Plan-tiered Does this well:Count and age flags
Who is on call for the tool itself Partly, or with a caveat:You are Does this well:They are Does this well:They are Partly, or with a caveat:You are
  • Does this well
  • Partly, or with a caveat
  • Not built
  • Works, but on their terms

The honest test

Open your current bill and ask what you actually touched last month. If these are all true, you are paying for a suite to use one row of it.

  • Your senders are Laravel apps, or you are happy to post one JSON envelope from anything else.
  • You never used the spam score or the client previews.
  • A CI step or an agent needs to count and check mail without reading customer bodies.

Then you lose very little by moving. The same slice runs on infrastructure you already pay for, with retention you set.

Keep paying them if

These are the parts we chose not to build, and we are not going to pretend otherwise.

  • You need spam scores or rendering checks across mail clients.
  • Non-Laravel services must send over plain SMTP with no code change.
  • You want to forward or release trapped mail to real recipients.
  • You want a vendor with an SLA rather than a repository where feature requests are a fork away.

Small, sharp tools are a deliberate scope, not an unfinished roadmap. Sink will not grow a deliverability suite.

Be honest about it

You don't need us to run Sink

The repository is public and MIT licensed. These are the steps, and you are welcome to spend the afternoon doing them by hand.

  1. 1

    Fork the Sink repository into your own GitHub organisation.

  2. 2

    Deploy the fork to Laravel Cloud with its own compute, Postgres, queue, object storage and scheduler, then create the first admin and invite your team.

  3. 3

    Issue a token per sending app, install the client, and switch its mail driver to sink.

Or let Scalpels do it, free. It forks the app, provisions exactly what it needs on your Laravel Cloud account, and deploys it. The app and the infrastructure are yours either way — the only question is who spends the afternoon.

Deploy Sink for free

Want some help?

After you buy, we will pay for an hour with one of these experts to help you get everything up and running.

  • Artisan Build

    USA

    We run Scalpels, as well as a suite of other tools for developers and development teams.

    Agency Ask for help
    Ask Artisan Build for help

Sink pairs with the rest of the suite

Sink, Hone and Matte are the same machine with a different payload: one token registry, one install command, one environment per client. A team already running either has the auth and provisioning story done.

Hone Matte Crate