Definition
sift.mx sender rules decide whether a contact is sifted in free (whitelist), held behind a cover, or sifted out (blocked).
Whitelist for people you know
Add addresses, domains, or chat handles you trust. Their traffic skips the cover so day-to-day work and relationships stay frictionless.
Cover for everyone else
The default for unknowns is pay-to-deliver at the cover you configure. That is the sift: intent costs something small, attention stays yours.
Block what should never arrive
Blacklist abusive senders or domains. Combined with authentication checks, this keeps obvious junk from even becoming a paid challenge.