A quiet hand
in a noisy barnyard.

Connect a Gmail mailbox and Brood begins, quietly. It reads the metadata of the mail you get and the mail you send: who wrote, when, from which domain, and who you write to. Not the subject line, which is never requested, and never the body: Brood holds the permission that filing mail requires, and never uses it to read.

First it reads the last 30 days, which is what its proposals rest on. On Pro it then reads further back, to 120 days, and keeps up with each message as it arrives.

The code that reads your Gmail is public, with the check that holds it to metadata, at github.com/Noisy-Brood/what-brood-reads.

Read it and you can see that every request able to return a message body asks for metadata instead, with a list of headers that leaves out the subject line.

It shows what we wrote, not what is running on the day you read it. And that no other part of Brood calls Gmail is checked on every change, over source that is not published, so for that half you have our word.

When one domain sends you 10 or more messages in 30 days, Brood proposes a home for it: a label of its own in Gmail, such as brood/ext/stripe. When 3 or more parts of one domain each do that, each gets a home within it.

It leaves some senders alone however often they write: the ones who must always reach you, anyone you write to, and your colleagues writing from your own work domain.

Nothing is filed until you say so. The clear cases are offered together, to file in one action, and you can leave out any you like; the rest come one at a time. A sender you decline is not proposed again.

It also notices who you write to and hear back from, and suggests them as customers. Confirm one, and Brood proposes a home for its mail too, which you confirm on its own.

Once you confirm a home, Brood files what is already there under its label and writes a filter in Gmail for what comes next, so new mail is filed as it arrives, before it reaches your inbox.

When a sender has not written for 60 days, Brood quiets its home: it moves the label under brood/quieted, and lists it on its Quieted page. Brood decides that on its own, and nothing is deleted: quieted mail is still in Gmail, still searchable.

If you move a sender's mail back out of its home 3 times in a row, Brood takes the hint. It removes the filter, and what was already filed stays where it is.

On Pro, where a mailing offers a one-click unsubscribe, Brood can ask the sender to stop, and tells you later whether it did.

A filed message comes back to your inbox when it replies in a conversation you wrote in within the last 7 days, or when a customer writes after 30 days of silence, the first time only.

When a quieted sender writes again, the first message comes back too, and Brood asks whether to wake the home. Anything more is filed there until you answer.

Some mail must always reach you: a password reset, a sign-in code, a fraud alert. Brood keeps a list of who always gets through. It starts with a few senders known to send security alerts, such as Google's account alerts and GitHub's security alerts, and you add your own: an address, a domain, a pattern, or an address copied on a message.

Every filter Brood writes leaves them out, and if one of their messages is filed anyway, Brood puts it back in your inbox. That is on every plan, free or not: safety is not a feature to sell.