You will receive an account inactivity message if you have not logged into your website for more than a month. Please refer to the article Why do I keep receiving no activity / login emails when I login frequently? to ensure your login is being recorded correctly. The automated system that sends these messages does not know that the school maybe on holiday, is content with their website (and so does not login), or for any other reason. It simply knows that no-one has logged in. Consequently this is why the email is sent.
If the website is not logged into during a school holiday which last more than a month, then you will receive a message. Simply logging into the website (not just visiting) will mark the website active for another month. Remember that the website will not be taken offline until another two months has passed after the first message has been received.
Please Note: We cannot stop or delay these messages just because the school may be on holiday.