There are several anti-spam measures in place, but this is basically how the main one works: When a client wallet tries to make too many transactions in a set period of time it will get kicked to the back of the queue, if it keeps it up it will be disconnected from the network for 10 minutes, if it keeps up the ban time increases, and so on.
This is just one measure, there are several more in place.
But please do try to spam it, check for yourself, it is really interesting to see how this works when you are trying.

Do ask if you have any further great questions! Thank you for the interest in x42.