I've been hosting several sites for years on my Linode server. For the first time I wanted to create one with email service, so I just go to "create virtual server" and make sure "accept mail for domain" and other related features are checked. However after it is created, all my websites on the same server were getting "403 forbidden" error, it seems to me those websites are all pointing to a different server, because when I try to open URL like "mywebsite.com/a_file_I_know_exist.php", it will return error saying "file not found" instead of "403 forbidden". After I delete the newly created virtual server, everything went back to normal?
Can anyone enlighten me about what could possibly be the cause?
My server is Ubuntu 16.04/PHP7.2/apache2.4