使用Google SMTP服务器（已用应用密码）仍报用户名密码不接受错误

尝试配置Spring Boot应用通过Google SMTP服务器发送通知，已生成App Password，但发送时始终提示认证失败。

应用配置（application.yaml） #

mail:
    host: smtp.gmail.com
    port: 587
    username: <username>
    password: <app-password>
    properties:
      mail:
        smtp:
          auth: true
          starttls:
            enable: true
        debug: true

控制台错误日志 #

DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "smtp.gmail.com", port 587, isSSL false
220 smtp.gmail.com ESMTP z21-20020a19f715000000b004eb44dae858sm1433785lfe.52 - gsmtp
DEBUG SMTP: connected to host "smtp.gmail.com", port: 587
EHLO Igor-PC
250-smtp.gmail.com at your service, [37.145.40.200]
250-SIZE 35882577
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
DEBUG SMTP: Found extension "SIZE", arg "35882577"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "SMTPUTF8", arg ""
STARTTLS
220 2.0.0 Ready to start TLS
EHLO Igor-PC
250-smtp.gmail.com at your service, [37.145.40.200]
250-SIZE 35882577
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
DEBUG SMTP: Found extension "SIZE", arg "35882577"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "AUTH", arg "LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH"
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "SMTPUTF8", arg ""
DEBUG SMTP: protocolConnect login, host=smtp.gmail.com, user=<username>, password=<non-null>
DEBUG SMTP: Attempt to authenticate using mechanisms: LOGIN PLAIN DIGEST-MD5 NTLM XOAUTH2 
DEBUG SMTP: Using mechanism LOGIN
DEBUG SMTP: AUTH LOGIN command trace suppressed
DEBUG SMTP: AUTH LOGIN failed
30959 [http-nio-9000-exec-1] WARN  o.a.a.s.u.RestorePasswordServiceImpl - Authentication failed; nested exception is javax.mail.AuthenticationFailedException: 535-5.7.8 Username and Password not accepted. Learn more at
535 5.7.8  https://support.google.com/mail/?p=BadCredentials z21-20020a19f715000000b004eb44dae858sm1433785lfe.52 - gsmtp

多次重置App Password仍无法解决，请问问题出在哪里？

按以下步骤逐一排查：

• 确认两步验证已开启：生成App Password的前提是Google账户必须开启两步验证，未开启的话生成的密码无效。
• 核对App Password生成参数：生成时应用类别选「Mail」，设备选「Other (Custom name)」，确保生成的是适用于邮件服务的密码。
• 检查用户名和密码格式：用户名必须是完整的Gmail邮箱地址（如xxx@gmail.com），App Password是16位无空格字符串，避免复制时带入多余字符。
• 补充SMTP安全配置：在application.yaml中添加SSL信任及超时配置，优化连接稳定性：

  mail:
    properties:
      mail:
        smtp:
          ssl:
            trust: smtp.gmail.com
          connectiontimeout: 5000
          timeout: 5000
          writetimeout: 5000
  

• 检查账户安全状态：登录Google账户安全中心，确认近期是否有异常登录拦截，若有需允许当前设备/IP的访问。
• 升级JavaMail版本：确保spring-boot-starter-mail依赖的JavaMail为最新稳定版，旧版本可能存在认证兼容性问题。

内容的提问来源于stack exchange，提问作者Igor