Your Message with subject Fw: bf was not delivered to some recipients
The following recipient(s) could not be reached
wu.hefung@yahoo.com
Remote server (98.136.216.25) issued an error.
MailServer sent: .
Remote server replied: 554 Message not allowed - [299]

退信原因：邮件内容被屏蔽，认定为垃圾邮件

解决方案：调整邮件的内容以及标准等再次发送即可，不要出现明显的广告性质的关键词，以免被对方认识是垃圾邮件，或者可以让客户将你的邮件地址加入白名单中，以便可以正常的通讯。