DAG exported buckets are synchronised with clients and are hence available in all environments. They may have secondary indices on them but may not have TTLs or create policy. Creating buckets and deciding what data is passed in them is up to you. System buckets will always be defined by default.

A good way to get started is to use the _email.tid bucket and add a small label in the email list. This will tag your emails accordingly and help you confirm that your filtering is accurate.

System buckets

The buckets below are created by the Red Sift framework, in addition to the buckets exported by a specific Sift.

_userAvailable on the frontend only, can be used to store user related information. This bucket is not synchronised with the backend or other frontends.
_email.idUsed by Redsift's email clients and extensions, it contains information specific to a given email, if emitted by the Sift's DAG.
_email.tidSame as _email.id but in this case refers to an email thread.
_redsiftinstalled/uuid: Installation instance ID
webhooks/[port]: a URL for the webhook to call. [port] = the name given in sift.json
_rpcOutput location for result of an RPC request.