Spend 10 minutes listing who actually needs your attention vs. who just likes to send things.
Settings → Filters → Create. Match on “from:(@clientdomain.com)” — domains beat individual addresses.
Skip inbox + apply label. Never auto-delete; you will need that one newsletter eventually.
Match “invoice” or “receipt” in subject, star + label so billing never buries itself.
Apply each filter to matching existing conversations — otherwise old mail stays a swamp.