当邮件使用SMTP协议身份认证时，如果出现

javax.mail.AuthenticationFailedException: 535 5.7.3 Authentication unsuccessful.

则说明你的用户名与你的密码不正确导致验证失败！

SMTP_AUTH_Fail_Response Message

SMTP_AUTH_Fail_Response is defined as follows. This message, identified by the 535 status code, is defined in [RFC2554] section 4, and indicates that the authentication has terminated unsuccessfully because the user name or password is incorrect.

 535 5.7.3 <human-readable-string><CR><LF>

详情见SMAP协议 SMAP

原文链接：https://blog.csdn.net/running_snail_/article/details/8767153