【以下均可删除】
提问前请务必仔细阅读 如何排查故障 和 常见问题。
问题描述（报错内容）：
在后台配置了邮箱，配置完成之后注册邮件可以正常发送，但是会提示错误。目前不清楚问题出现在哪里
同时：在后台点击测试发送，也是有同样的问题。
已尝试的解决办法（演示网址或图片）：
目前尝试了更换了其他的 QQ 邮箱也是会出现该问题，求助这个问题应该怎么解决？
————更新————–
打开 debug 之后，得到以下错误信息：
POST https://www.vanlifetalks.com/api/mail/test
<br />
<b>Deprecated</b>: Callables of the form [“Swift_SmtpTransport”, “Swift_Transport_EsmtpTransport::construct”] are deprecated in <b>/www/wwwroot/www.vanlifetalks.com/vendor/swiftmailer/swiftmailer/lib/classes/Swift/SmtpTransport.php</b> on line <b>36</b><br />
<br />
<b>Deprecated</b>: Callables of the form [“Swift_Message”, “Swift_Mime_SimpleMessage::construct”] are deprecated in <b>/www/wwwroot/www.vanlifetalks.com/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Message.php</b> on line <b>46</b><br />
<br />
<b>Deprecated</b>: Exception::__construct(): Passing null to parameter #2 ($code) of type int is deprecated in <b>/www/wwwroot/www.vanlifetalks.com/vendor/swiftmailer/swiftmailer/lib/classes/Swift/SwiftException.php</b> on line <b>26</b><br />
<br />
<b>Fatal error</b>: Uncaught Laminas\HttpHandlerRunner\Exception\EmitterException: Output has been emitted previously; cannot emit response in /www/wwwroot/www.vanlifetalks.com/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:20
Stack trace:
#0 /www/wwwroot/www.vanlifetalks.com/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitterTrait.php(42): Laminas\HttpHandlerRunner\Exception\EmitterException::forOutputSent()
#1 /www/wwwroot/www.vanlifetalks.com/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitter.php(21): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->assertNoPreviousOutput()
#2 /www/wwwroot/www.vanlifetalks.com/vendor/laminas/laminas-httphandlerrunner/src/RequestHandlerRunner.php(75): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->emit()
#3 /www/wwwroot/www.vanlifetalks.com/vendor/flarum/core/src/Http/Server.php(45): Laminas\HttpHandlerRunner\RequestHandlerRunner->run()
#4 /www/wwwroot/www.vanlifetalks.com/public/index.php(26): Flarum\Http\Server->listen()
#5 {main}
thrown in <b>/www/wwwroot/www.vanlifetalks.com/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php</b> on line <b>20</b><br />