<?php

    $mailer = new Mailer;
    
    $mailer->authorize(true);

    $mailer->server('mail.server'); 
    
    $mailer->setup([

        'client' => ['name' => 'Foo']

    ]);

    $mailer->sendmail('mail.template');
    
    if($mail->sent('online') || $mail->sent('offline')) {      

        
        //... mail was situationally forwarded. 
        

    }
    

In the example above, notice that the online and offline parameters were supplied as strings not constants. The sent('online') was used to check if a mail was truly sent in online mode. For this to work, success response has to be returned by the PHPMailer in an online environment after a message has been sent. If the first test fails, then sent('offline') checks if the environment was offline and mail was casted in that offline environment. If the second argument tests postive, then the code block is executed. The second test will only return positive for an offline environment where a mail is casted. By default, the sent() method is set for an online environment. So $mail->sent() returns positive only when a message is truly sent in online environment.