Customers on any paid plan have the option of exceeding their plan’s monthly sending limit. In that case, an overage fee will be incurred for each email that exceeds the monthly sending limit. Pricing plan details identify the overage fee.
Free test accounts are capped with a limited sending volume.
If you know you are going to exceed your monthly sending limit prior to sending and would prefer not to incur overages, it’s easy to upgrade your plan within the app to accommodate your higher sending needs.