Using cash to buy multiple cashier's checks over a period of time is considered suspicious activity of money laundering. This method is commonly known as structuring, where individuals or entities use cash to buy multiple monetary instruments such as cashier's checks in small amounts, to avoid reporting requirements. This behavior could be an attempt to evade transaction monitoring and reporting requirements by a financial institution. Additionally, the fact that the account also receives multiple electronic transfers for the same amount could be a red flag for money laundering as it is a common technique used to layer or disguise the origin of illicit funds.