I can only use smtp to send email and I set it in setting.php. However, it does not work. 

$CONFIG->emailer_transport = 'smtp';

$CONFIG->emailer_smtp_settings = array(

'name'              => 'noreply@***.***.***',

'host'              => '***.***.***',

'connection_class'  => 'login',

'connection_config' => [

'username' => 'noreply@***.***.***',

'password' => '*******',

'ssl'      => 'tls', // OPTIONAL (tls or ssl)

'port'     => '465', // OPTIONAL (Non-SSL default 25, SSL default 465, TLS default 587)

'use_complete_quit' => '', // OPTIONAL

],

);

Is it right? And my server bans port 25 but 465 is ok. 

It makes me mad:( I know it is a strange questions with so many things to deal with. Other options are ok.