I've installed it from the beginning, creating a new AWS account.
First of all, I have created my account, creating the SMTP credentials.
After that, I've verified both, sender and receiver addresses in the verifier senders section
https://console.aws.amazon.com/ses/home#verified-senders-emailAfter that, I've sent a test mail clicking the "send test email" button
When it has worked, I've gone to the Mantis config file, to installdir/apps/mantis/htdocs/config_inc.php and added these lines
$g_phpMailer_method = PHPMAILER_METHOD_SMTP; #For SMTP Method
$g_smtp_host = 'email-smtp.us-east-1.amazonaws.com'; #Your SES SMTP Host
$g_smtp_connection_mode = 'tls'; #It is mandatory for SES and Gmail SMTP
$g_smtp_port = 587; #For some Reason only this port was working in SES
$g_smtp_username = 'mySMTPuser'; # Your SES SMTP Username
$g_smtp_password = 'mySMTPpassword'; # Your SES SMTP Password
$g_administrator_email = 'verified sender email'; #Email displayed at footer (Must be an approved sender list in SES)
$g_webmaster_email = 'verified sender email'; #Verified SES Sender Email
$g_from_email = 'verified sender email'; # From Address (Verified SES Sender Email)
$g_return_path_email = 'verified sender email'; # the return address for bounced mail
$g_from_name = 'My Name';
$g_enable_email_notification = ON;
Then I've gone to Mantis app, I've created a new user with email the verified receiver SES Email, and the app has sent to me the notification. So it's working perfectly.
Please, check in the link above the Amazon SES metrics, to see whether the mails are sent or not.