Mailwizz群发邮件系统近期更新邮件框架，由SwiftMailer改为Symfony，在系统中有提示升级：
SwiftMailer is deprecated And we are planning to remove it from MailWizz. In order to prepare for this change, enable the Symfony Mailer instead, from Backend > Settings > Common, then verify your delivery servers and make sure they work as expected.
具体操作：
最后进行测试发送服务器即可。