javaMail not working with OAuth gmail send email - oauth-2.0

Question

javaMail: send mail using google oauth caused javax.mail.AuthenticationFailedException.
Properties props = new Properties();
props.put("mail.smtp.ssl.enable", "true"); // required for Gmail
props.put("mail.smtp.auth.mechanisms", "XOAUTH2");
Session session = Session.getInstance(props);
Transport transport = session.getTransport("smtps");
transport.connect("smtp.gmail.com", 465, xyz#gmail.com, oauth_access_token);
The oauth access token is valid, just refreshed, about 20 seconds before running the code.
Error:
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 s136sm158338qka.106 - gsmtp
at com.sun.mail.smtp.SMTPTransport$Authenticator.authenticate(SMTPTransport.java:965)
at com.sun.mail.smtp.SMTPTransport.authenticate(SMTPTransport.java:876)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:780)
at javax.mail.Service.connect(Service.java:366)
From the logging, it seems that auth is using username/password, not OAUTH. guide: https://javaee.github.io/javamail/OAuth2
Logging:
DEBUG: JavaMail version 1.6.2
DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Oracle]
DEBUG SMTP: useEhlo true, useAuth false
DEBUG SMTP: trying to connect to host "smtp.gmail.com", port 465, isSSL true
220 smtp.gmail.com ESMTP s136sm158338qka.106 - gsmtp
DEBUG SMTP: connected to host "smtp.gmail.com", port: 465
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=xyz#gmail.com, 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

Answer 1

In case someone comes across this page: JavaMail does work with Gmail OAuth2 authentication. The following is how it works on my Kotlin code base:
The props needed for Session is shown below (it's in yaml format, but you get the idea):
javamail:
config:
"mail.smtp.host": smtp.gmail.com
"mail.smtp.port": 587
"mail.smtp.starttls.enable": true
"mail.smtp.starttls.required": true
"mail.smtp.auth.mechanisms": XOAUTH2
When constructing an email (multi-part or not), the enclosing mime message must be bound to a Session that has all the above props. This can be easily missed when using a class from a library to construct an email (like SimpleEmail):
val session = Session.getInstance(javamail.config().toProperties())
val email = SimpleEmail().apply {
setMailSession(session) // do not forget this line
setCharset("utf-8")
setFrom(credInfo.email())
addTo("someone#somewhere.com")
setSubject("Test email")
setMsg("This is the test.")
buildMimeMessage()
}
Call a static method Transport.send(msg, username, password), where username is your email, and password is your fresh access-token. There's no need to create an instance of Transport, nor a need to call transport.connect():
Transport.send(email.mimeMessage, gmail, accessToken)

Answer 2

I think you need to disable the plain authentication to force Jakarta Mail to use XOAUTH2.
props.put("mail.smtp.auth.plain.disable", "true");

Answer 3

Trying the following code:
Properties props = new Properties()
props.setProperty("mail.smtp.host", "smtp.gmail.com")
props.setProperty("mail.smtp.port", "587")
props.put("mail.smtp.auth","true")
props.put("mail.smtp.starttls.enable", "true")
props.put("mail.smtp.starttls.required", "true")
props.put("mail.smtp.auth.mechanisms", "XOAUTH2")
props.put("mail.smtp.auth.login.disable", "true")
props.put("mail.smtp.auth.plain.disable", "true")
props.put("mail.smtp.auth.ntlm.disable", "true")
props.put("mail.debug", "true")
props.put("mail.debug.auth", "true")
Session session = Session.getInstance(props)
String emptyPassword = ""
final URLName unusedUrlName = null
SMTPTransport transport = new SMTPTransport(session, unusedUrlName)
transport.connect("smtp.gmail.com", googleEmail, googleAccessToken)\
Multipart multipart = new MimeMultipart()
BodyPart messageBodyPart = new MimeBodyPart()
def from = googleEmail
def to = "test#test.com"
def subj = "TestOath2Gmail"
def body = "TTT"
message.setFrom(new InternetAddress(googleEmail))
message.addRecipient(javax.mail.Message.RecipientType.TO, new InternetAddress(to))
Date sentDate = new Date()
message.setSentDate(sentDate)
message.setSubject(subj)
messageBodyPart.setContent(body, "text/html")
multipart.addBodyPart(messageBodyPart)
message.setContent(multipart)
transport.send(message)
Getting error:
DEBUG SMTP: Using mechanism XOAUTH2
AUTH XOAUTH2
235 2.7.0 Accepted
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle]
DEBUG SMTP: need username and password for authentication
DEBUG SMTP: protocolConnect returning false, host=smtp.gmail.com, user=username, password=