By provider
Google, Microsoft and the rest, each with its own inbox-versus-spam count.
Placement
Know where you land before you send.
Send a test to seed inboxes at Google, Microsoft and the rest. See inbox versus spam by provider, for every sending inbox. Included on every plan.
Per sending inbox
Find the one inbox dragging the rest down before it costs you a campaign.
Run it any time
Before a launch, after a warm-up, whenever something feels off.