Styjun

I was using the older JavaMail API to send email from my Android app using password based authentication. The thing is that I am using my own GMail account for sending email (thus storing email/password in code - I know that is not a good idea)

new PasswordAuthentication(_user, _pass)

I have now upgraded to the newer version of JavaMail and I want to use OAuth2

implementation 'com.sun.mail:android-mail:1.6.2'
implementation 'com.sun.mail:android-activation:1.6.2'

How do I generate OAuth credentials for my own GMail account and use them to send email?

EDIT:

This is what I tried so far:

1. Created a project on Google Console. From the Credentials screen, create OAuth Client ID - choose "Other". This gives me Client ID and Client Secret


2. Using oauth2.py, used the Client ID and Client Secret to generate an Access Token and a Refresh Token (In the production app, I intend to hard code all 4: client id, secret, access, refresh token and continue using them "forever" for generating new access tokens)


3. Tested that SMTP Authentication works using oauth2.py


4. 
   

   Modified my Java code for sending the mail as follows:

   
   
   

   Properties props = new Properties();
   props.put("mail.smtp.host", "smtp.gmail.com");
   props.put("mail.debug", "true");
   props.put("mail.smtp.port", 587);
   props.setProperty("mail.smtp.socketFactory.port", 587);
   props.put("mail.smtp.auth", "true");
   props.put("mail.smtp.starttls.enable", "true");
   props.put("mail.smtp.auth.mechanisms", "XOAUTH2");
   
   Session session = Session.getInstance(props);
   SMTPTransport transport = new SMTPTransport(session, null);
   transport.connect("smtp.gmail.com", _user, _accessToken);
   transport.sendMessage(msg, msg.getAllRecipients());
   

   
   

And now I am getting:
java.net.UnknownHostException: mail.google.com Unknown SMTP host: smtp.gmail.com

I am having trouble finding how to set the Access Token on the request. Instead of

transport.connect("smtp.gmail.com", _user, _accessToken);

I have also tried

String auth = new String(BASE64EncoderStream.encode(String.format("user=%s1auth=Bearer %s11", _user, _accessToken).getBytes()));
transport.issueCommand("AUTH XOAUTH2 " + auth, 235);

But same error.