550 SPF check failed
退信内容:550 SPF check failed. http://service.mail.qq.com/c…
退信内容:550 Domain may not exist or DNS check failed [NX9W…
退信内容:550 5.7.1 xxx@xxx.xx may not send mail to <xxx@…
退信内容: 550 Service unavailable; Client Host [xx.xx.xx.xx…
退信内容:550 Requested action not taken:Invalid IP<xx.xx…