[Mailer] Update docs for sendmail -t

Author: fabpot

Transport/SendmailTransport.php

@@ -23,10 +23,6 @@
 /**
  * SendmailTransport for sending mail through a Sendmail/Postfix (etc..) binary.
  *
- * Supported modes are -bs and -t, with any additional flags desired.
- * It is advised to use -bs mode since error reporting with -t mode is not
- * possible.
- *
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Chris Corbyn
  */
@@ -39,11 +35,14 @@ class SendmailTransport extends AbstractTransport
     /**
      * Constructor.
      *
-     * If using -t mode you are strongly advised to include -oi or -i in the flags.
-     * For example: /usr/sbin/sendmail -oi -t
-     * -f<sender> flag will be appended automatically if one is not present.
+     * Supported modes are -bs and -t, with any additional flags desired.
      *
      * The recommended mode is "-bs" since it is interactive and failure notifications are hence possible.
+     * Note that the -t mode does not support error reporting and does not support Bcc properly (the Bcc headers are not removed).
+     *
+     * If using -t mode, you are strongly advised to include -oi or -i in the flags (like /usr/sbin/sendmail -oi -t)
+     *
+     * -f<sender> flag will be appended automatically if one is not present.
      */
     public function __construct(string $command = null, EventDispatcherInterface $dispatcher = null, LoggerInterface $logger = null)
     {