使用Sendmail通过AWS SES发件时Gmail服务器拒收，Outlook可正常接收的问题排查求助

各位好，我最近碰到个棘手的问题：我用Sendmail搭配AWS SES发送邮件，Outlook那边能顺利接收，但Gmail服务器直接拒收了请求。有没有大佬能帮我排查下问题出在哪？多谢了！

下面是相关的服务器日志：

Gmail拒收相关日志 #

Oct 30 05:38:06 v*******5 sm-mta[19968]: 39U5c6nN019966: to=*****@gmail.com, delay=00:00:00, xdelay=00:00:00, mailer=esmtp, pri=120977, relay=gmail-smtp-in.l.google.com. [IPv6:2607:f8b0:4023:1002::1a], dsn=5.0.0, stat=Service unavailable

Oct 30 05:38:06 v*******5 sm-mta[19968]: 39U5c6nN019966: 39U5c6nN019968: DSN: Service unavailable

Oct 30 05:38:07 v5 sm-mta[19968]: 39U5c6nN019968: to=<noreply@cdl-lb-.us-east-1.elb.amazonaws.com>, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=30000, relay=cdl-lb-*******....elb.amazonaws.com. [34.234.182.53], dsn=4.0.0, stat=Deferred: Connection refused by cdl-lb-********.us-east-1.elb.amazonaws.com.

Outlook正常接收相关日志 #

Oct 30 05:37:00 v5 sm-mta[19873]: 39U5aurD019871: to=******@nexsales.com, delay=00:00:04, xdelay=00:00:04, mailer=esmtp, pri=120978, relay=n-com.mail....ction.outlook.com. [52.101.132.30], dsn=2.0.0, stat=Sent (<6***@*****k.com> [InternalId=114993454396419, Hostname=KL1PR0401MB4340.apcprd04.prod.outlook.com] 10024 bytes in 0.301, 32.520 KB/sec Queued mail for delivery)

备注：内容来源于stack exchange，提问作者Rahul Gupta