PHP：如何在Linux上测试邮件到localhost并实际接收它？

I'm building a daemon in php that checks for received emails which it then stores in the database leading them through a whole process. The thing is that I want to build some unit tests for this, for which I don't want to setup a whole mail server. So for tests I want to somehow send emails to localhost, which should then be picked up by the daemon and processed further. So I tried the following:I'm building a daemon in php that checks for re