As its name suggests, the Check My Email tab is supposedly a tool for easier access to checking one’s email. However, it is found out to be a browser hijacker that will attempt to commandeer a user’s browser search to this homepage: https://query.hcheckmyemail.co/s. This browser hijacker will direct search results to malicious websites to get money from you or infect your computer further. It may also prevent you from changing your settings back.
The Check My Email tab is usually installed through bundled software without you knowing. Remove it immediately.