发给所有其他邮箱均无问题 到任何Gmail邮箱都被Google退信回来，提示如下

Final-Recipient: rfc822; [email protected]
Action: failed
Status: 5.7.1
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.1 [2400:8900::f03c:91ff:fe84:3587 12] Our
system has detected that 550-5.7.1 this message is likely unsolicited mail.
To reduce the amount of spam 550-5.7.1 sent to Gmail, this message has been
blocked. Please visit 550-5.7.1
http://support.google.com/mail/bin/answer.p抗投诉服务器y?hl=en&answer=188131 for 550
5.7.1 more information. os5si13792594pab.197 - gsmtp

unsolicited mail应该是被当spam了吧 能确认此前从来没发过任何spam或被黑用来发过spam，而且貌似就是换到Linode东京以后才出的问题 难道是这IP原来有过记录被拉黑了
肯定是ip被拉黑了。

1.这是错误号解释
550, "5.7.1", Email quota exceeded.
550, "5.7.1", Invalid credentials for relay.
550, "5.7.1", Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been blocked. Review our Bulk Email Senders Guidelines.
550, "5.7.1", Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. For more information, review this article.
550, "5.7.1", The IP you're using to send mail is not authorized to send email directly to our servers. Please use the SMTP relay at your service provider instead. For more information, review this article.
550, "5.7.1", The user or domain that you are sending to (or from) has a policy that prohibited the mail that you sent. Please contact your domain administrator for further details. For more information, review this article.
550, "5.7.1", Unauthenticated email is not accepted from this domain.
2.一个关于 ipv6 的提示
Here is the text from google's help page ( https://support.google.com/mail/answer/81126 ):
Additional guidelines for IPv6
The sending IP must have a PTR record (i.e., a reverse DNS of the sending IP) and it should match the IP obtained via the forward DNS resolution of the hostname specified in the PTR record. Otherwise, mail will be marked as spam or possibly rejected.
The sending domain should pass either SPF check or DKIM check. Otherwise, mail might be marked as spam.
不知道对你有没有帮助～

去谷歌/大的反垃圾组织看看有没有被拉黑，spf有没有做好，看看发信人是不是localhost

你的服务器lP未作域名反向解析。。。。