Core

This check takes the php.ini settings into account, no matter what settings exist in LocalConfiguration.php.
During the installation the Environment Check is executed, before LocalConfiguration.php even is created.
So this test can provide misleading information, reporting broken mail functionality, even when it works just fine with the settings given in LocalConfiguration.php.
So we decided to remove this test in Environment Check entirely and enhance the documentation on the real mail test in Test Setup with some hints, what can be wrong when no mail is received.
In short order the autoconfiguration tool will be introduced. This will reintegrate the test with some sane default configuration, not relying on the php.ini settings.