After those third-party scammers obtain your email password, they will not do anything immediately, but will observe your mailbox to see if there is an order that is about to be paid recently.
Once get the target, they will start a new email address, which is very similar to your supplier/buyer. Just like below. You might not find the differences after sending so many emails to your supplier.
Then intercept the e-mail with the bank information sent to you by the supplier, and send you their bank account information to get the payment. Their bank accounts are usually opened in places with loose financial regulations such as the Cayman Islands or Hong Kong where funds can flow in and out freely.
Once the funds are obtained, the money in the account will be immediately transferred away, and the source cannot be traced.
Once our payment is defrauded, it will be extremely difficult to recover our losses. So please pay attention to your mailbox when you want to send money.