Mail servers sometimes modify email in transit. This can invalidate the domainkeys signature. dkim-milter supports two canonicalization algorithms. Thesimplealgorithm tolerates almost no modification. Therelaxedalgorithm tolerates common modifications such as white-space replacement and header line re-wrapping...
也就是说MTA 到MTA之间转发邮件是不需要认证的，这是SMTP协议本身定义的。
dkim=pass (2048-bit key; unprotected) header.d=gmail.com[email protected]header.b="XWMRd2co"; dkim-atps=neutral Configuration Error in Email Client DKIM signing could fail if you don’t use the correct SMTP/IMAP settings in your email client. Correct Settings: SMTP protocol: entermail.you...