已尝试的解决办法（演示网址或图片）：尝试更新swiftmailer/swiftmailer至6.3，无法解决。尝试迁移到symfony/mailer，无法解决。尝试切换php版本，无法解决。邮件可以正常发送，但是一直提示该错误。
错误提示😃eprecated: Callables of the form [“Swift_SmtpTransport”, “Swift_Transport_EsmtpTransport::__construct”] are deprecated in /www/wwwroot/www.test.com/vendor/swiftmailer/swiftmailer/lib/classes/Swift/SmtpTransport.php on line 36
Deprecated: Callables of the form [“Swift_Message”, “Swift_Mime_SimpleMessage::__construct”] are deprecated in /www/wwwroot/www.test.com/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Message.php on line 46
Fatal error: Uncaught Laminas\HttpHandlerRunner\Exception\EmitterException: Output has been emitted previously; cannot emit response in /www/wwwroot/www.test.com/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:20 Stack trace: #0 /www/wwwroot/www.test.com/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitterTrait.php(42): Laminas\HttpHandlerRunner\Exception\EmitterException::forOutputSent() #1 /www/wwwroot/www.test.com/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitter.php(21): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->assertNoPreviousOutput() #2 /www/wwwroot/www.test.com/vendor/laminas/laminas-httphandlerrunner/src/RequestHandlerRunner.php(75): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->emit() #3 /www/wwwroot/www.test.com/vendor/flarum/core/src/Http/Server.php(45): Laminas\HttpHandlerRunner\RequestHandlerRunner->run() #4 /www/wwwroot/www.test.com/index.php(26): Flarum\Http\Server->listen() #5 {main} thrown in /www/wwwroot/www.test.com/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php on line 20