There are periods where you may receive more SPAM than usual. There are several reasons for this.
Our SPAM filters adapt to the cirumstances. As more SPAM comes in, it will start learning to filter it. This may take time depending on the type of SPAM and the amount. It is important also that you move the SPAM messages that were missed by the filter into the Spam folder. This way, our internal system can collect it overnight.
It is also very common that computers across the globe get infected with some virus that starts sending SPAM with the email address of your contact. It is difficult to stop this kind of SPAM as most of the time it appears from a legit source.