What Is a “Transaction Spam” Attack and How Do Fees Mitigate It?

A transaction spam attack is an attempt to flood the network with a large number of low-value or non-essential transactions to congest the mempool and slow down confirmation times for legitimate users. The goal is often to disrupt the network's usability.

Fees mitigate this attack by introducing a cost to the attacker. Since every transaction requires a fee to be confirmed, a sustained spam attack becomes prohibitively expensive for the attacker, as they must continuously pay miners for the block space they consume.

This economic disincentive acts as a primary defense mechanism.