How does php mail function know which mail server to use?

I'm working开发者_高级运维 on existing project and I see that we make a call to mail function, however I don't see anywhere where we specify smtp server name password etc... My guess it is in some file but where?

You can configure the behavior of the mail functions in php via the php.ini, and some can be set with ini_set (per http://www.php.net/manual/en/configuration.changes.modes.php)

Email configuration options can be found here: http://www.php.net/manual/en/mail.configuration.php

That's because it uses the local OS "mail" command. It uses whatever the operating system is configured to use. If you want to use and SMTP server, name and password, use SwiftMailer.