Order status bought events

Hi,
General question about the order status of events that are paid by customers. I am using the e-mails connected to the ‘Processing’ status. Lately some orders went to ‘Completed’ right away. As a consequence customers are missing out on the e-mail with the invoice.
I read that only virtual and downloadable products can switch to ‘Completed’ right away, but I cannot find how this works for events. Or even better, how can I make sure every order gets the status ‘Processing’ until my client manually changes the status?
Best!