"When it comes to your inbox, the sparking joy question is: 'Do I have a next action on this?' You should be asking yourself that with every email. If the answer is yes, immediately, put it in the corresponding folder (i.e. To Read). Many people open an email once but then mark it as unread again, confusing their brain as to whether it’s new or if they already saw it. If the answer is 'no next action,' archive or delete it. People get overwhelmed when they leave things around that they might need later or may want to reference one day. Those things don't have an immediate next action or spark joy, so they should be purged (right after you thank those emails for their service, like Marie Kondo does!).