Paid plans begin at public launch, and fair-use rate limits apply to every key.
Why per Gmail account?Each connected inbox is its own OAuth grant, its own quota, its own responsibility. One plan covers one inbox; connect a second inbox, add a second plan. No seats, no surprises.
What counts as a mailbox?One scoped, read-only view, like "only invoices" or "only github.com", with its own keys. The free plan includes one; Pro makes them unlimited.
Why is the AI filter free?Because it's the best part. Describing a mailbox in plain words is how allowemail is meant to be used, so every plan has it. The free plan is limited by mailbox count, never by features.