The Inbox collects what has happened that involves you: mentions, work assigned to you, due dates, updates on records you follow, and agents needing input.
Treat it like email you are allowed to be ruthless with. Each item is one of three things:
An inbox you clear daily is useful. One at 400 unread is furniture.
What lands here is set in Profile → Settings → Notifications, per category and per channel. In-app controls the Inbox; push and email decide whether the same event also reaches you elsewhere.
If the Inbox is too noisy, turn off Item updates first — it is the highest-volume category and rarely needs a person.
Replies to your support tickets appear in the Help center under My tickets, not in the Inbox, so a conversation with us cannot bury a mention from a colleague.
Related: Your profile and notifications · Notifications aren't arriving · Comments and mentions