发送QQ SMTP邮件遇到发送者邮箱必须与认证邮箱不一致的问题 [ 2.0 版本 ]

yes！ must be the same.
You can config like this, then you don't need to set mail from when send mails.

'mailer' => [
            'class' => 'yii\swiftmailer\Mailer',
            'useFileTransport' => false,//set this property to false to send mails to real email addresses
            //comment the following array to send mail using php's mail function
            'transport' => [
                'class' => 'Swift_SmtpTransport',
                'host' => 'smtp.yeah.net',
                'username' => 'flyfame@yeah.net',
                'password' => 'ddd',
                'port' => '587',
                'encryption' => 'ssl',
            ],
            'messageConfig' => [
                'charset' => 'UTF-8',
                'from' => ['flyfame@yeah.net'=>'系统邮件'],
            ],
        ],