JavaMail使用163，sina邮箱，发送失败，前几个月还是可用的。同样的代码，没有修改，是不是这些邮箱改了认证措施，pop/smtp设置也都开启了

DEBUG SMTP: connected to host "smtp.163.com", port: 25

EHLO DESKTOP-03CS8IQ

250-mail

250-PIPELINING

250-AUTH LOGIN PLAIN

250-AUTH=LOGIN PLAIN

250-coremail 1Uxr2xKj7kG0xkI17xGrU7I0s8FY2U3Uj8Cz28x1UUUUU7Ic2I0Y2UFILL8vUCa0xDrUUUUj

250-STARTTLS

250 8BITMIME

DEBUG SMTP: Found extension "PIPELINING", arg ""

DEBUG SMTP: Found extension "AUTH", arg "LOGIN PLAIN"

DEBUG SMTP: Found extension "AUTH=LOGIN", arg "PLAIN"

DEBUG SMTP: Found extension "coremail", arg "1Uxr2xKj7kG0xkI17xGrU7I0s8FY2U3Uj8Cz28x1UUUUU7Ic2I0Y2UFILL8vUCa0xDrUUUUj"

DEBUG SMTP: Found extension "STARTTLS", arg ""

DEBUG SMTP: Found extension "8BITMIME", arg ""

DEBUG SMTP: Attempt to authenticate using mechanisms: LOGIN PLAIN DIGEST-MD5 NTLM

DEBUG SMTP: AUTH LOGIN command trace suppressed

DEBUG SMTP: AUTH LOGIN failed

javax.mail.AuthenticationFailedException: 535 Error: authentication failed

at com.sun.mail.smtp.SMTPTransport$Authenticator.authenticate(SMTPTransport.java:892)

at com.sun.mail.smtp.SMTPTransport.authenticate(SMTPTransport.java:814)

at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:728)

at javax.mail.Service.connect(Service.java:364)

at javax.mail.Service.connect(Service.java:245)

at com.vino.javamail.JavaMailUtils.send(JavaMailUtils.java:60)

at com.vino.webresume.controller.MailServlet.doPost(MailServlet.java:46)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

找到原因了，163现在要使用授权码登录，而不是邮箱密码

有些免费邮箱是没有开通pop smtp的。所以必须得申请之后才能使用