我有以下配置来使用Google的服务帐户获取访问令牌，使用访问令牌进行OAUTH2身份验证并通过SMTPTransport连接。
以下是邮件会话属性：

<mailSession description="SMTP javax.mail.session" from="someone.iam.gserviceaccount.com">
    <property name="mail.smtp.host" value="smtp.gmail.com"/>
    <property name="mail.smtp.auth" value="true"/>
    <property name="mail.smtp.port" value="587"/>
    <property name="mail.smtp.ssl.enable" value="false"/>
    <property name="mail.smtp.sasl.enable" value="true"/>
    <property name="mail.smtp.ehlo" value="false"/>
    <property name="mail.smtp.sasl.mechanisms" value="XOAUTH2"/>
    <property name="mail.smtp.auth.plain.disable" value="true"/>
    <property name="mail.smtp.auth.login.disable" value="true"/>
    <property name="mail.smtp.starttls.required" value="true"/>
    <property name="mail.smtp.ssl.protocols" value="TLSv1.2"/>
    <property name="mail.smtp.connectiontimeout" value="10000"/>
</mailSession>

使用Google服务帐户凭据获取访问令牌：

try (FileInputStream serviceAccountStream = new FileInputStream(credentialsPath)) { 
    credentials = ServiceAccountCredentials.fromStream(serviceAccountStream).createScoped(Collections.singleton("https://mail.google.com/"));
    credentials.refresh();
    accessToken = credentials.getAccessToken();
    System.out.println("Access token2: " + accessToken.getTokenValue());
}

accessToken保存访问令牌对象。我已经观察了令牌，并确认结构似乎有效。即yaxx.c.dxVaekmxICgknK
根据JavaMail 1上的文档，这就是发生错误的地方。5.5+，认证如下：

SMTPTransport transport = new SMTPTransport(session, null);
transport.connect("smtp.gmail.com", 587, "sender@example.com", accessToken);

以上操作失败，并出现以下错误（私有值已被编辑）：

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=sample-service@gmail.iam.gserviceaccount.com, password=<non-null>
DEBUG SMTP: Authenticate with SASL
DEBUG SMTP: SASL mechanisms allowed: XOAUTH2
DEBUG SMTP: SASL Mechanisms:
DEBUG SMTP:  XOAUTH2
DEBUG SMTP: 
DEBUG SMTP: SASL client XOAUTH2
DEBUG SMTP: SASL callback length: 2
DEBUG SMTP: SASL callback 0: javax.security.auth.callback.NameCallback@66fdec9
DEBUG SMTP: SASL callback 1: javax.security.auth.callback.PasswordCallback@57abad67
AUTH XOAUTH2 dXNlcj1zYW1wbGUtc2VydmljZUBnbWFpbC5pYW0uZ3NlcnZpY2VhY2NvdW50LmNvbWF1dGg9QmVhcmVyIHlhMjkuYy5iMFZoZHNTVUhBanNvSldTT0lXU3VkbHNqc25zaXVoc2xpdW5hdVNVSDEzOHJsczgzbGFqYXFhaGhzOHVzaWRmamhza3VkYWRESAo=
555 5.5.2 Syntax error, goodbye. f17-40040a170904ab9100b001922d98cb4esm19571022plr.288 - gsmtp
DEBUG SMTP: SASL authentication failed
javax.mail.AuthenticationFailedException: failed to connect
    at javax.mail.Service.connect(Service.java:403)

发送方和接收方的格式为：“ www.example.com ”
我能够进行身份验证，从而连接时，使用谷歌应用程序密码（与适当的属性），但不是这个。我也试过委托用户，但这不是问题所在。为什么我们得到这个
我尝试了不同格式的邮件（e。g using〈〉）我曾尝试购买一个G-suite以便委派用户
我希望能够运输。连接和运输。sendMessage使用OAuth2。0，即我的服务帐户和令牌作为密码传递