Mac Mail comes with built-in junk mail filters that are designed to keep spam out of your inbox; these spam filters are automatically enabled, but can be manually disabled for whatever reason. Unlike some email handling functionality elsewhere in the application, these spam filtering settings are actually applied "program-wide" - in other words, you cannot filter spam for one email account, but ignore junk mail and keep it in your main mailbox for another account. In this tutorial, we will show you how to disable your junk mail filters in Apple Mail.
This is all you need to do to turn off your spam filters in Mac Mail; from this point on, all your email messages will remain inside your inbox. While junk mail filters are either On or Off for the entire email program and all accounts it contains, you can customize your Junk mailbox behavior options to handle automated spam deletion.