RT is not sending notification emails

It’s my first time using RT, so I used the basic installation guide InstallationGuides - Request Tracker Wiki

At the end it seems to be working fine, but I set it up to send an email every time a ticket is created and it is not sending the emails.

My RT_SiteConfig
use utf8;

Set( $Timezone, ‘America/Costa_Rica’);
Set( $CommentAddress, ‘xxxx.comments@email.com’ );
Set( $CorrespondAddress, ‘xxxx.mail@email.com’ );
Set( $DatabaseHost, ‘localhost’ );
Set( $DatabaseName, ‘rt4’ );
Set( $DatabasePassword, ‘xxxx’ );
Set( $DatabasePort, ‘’ );
Set( $DatabaseType, ‘mysql’ );
Set( $DatabaseUser, ‘rt_user’ );
Set( $Organization, ‘rt.example.com’ );
Set( $OwnerEmail, ‘xxxx@email.com’ );
Set( $SendmailPath, ‘/usr/sbin/sendmail’ );
Set( $MailCommand, ‘sendmail’);
Set( $SendmailArguments,“-oi -ODeliveryMode=b -OErrorMode=m”);
Set( $WebDomain, ‘localhost’ );
Set( $WebPort, ‘80’ );
Set( $rtname, ‘rt.example.com’ );
Set( $WebPath, ‘/rt’);
1;

Thanks.