cannot send email using gmail account from android using javax

Question

Error sending email:

returns 451 4.5.0 SMTP protocol violation, see RFC 2821 g5sm13340466pfg.0 - gsmtp.

After getting the oauth token, type and oauth expire from gmail.

here the following code used to test send email using oauth2.

private String GenerateOAuth2String(boolean base64_encode){
        String OAuthString = "";
        Log.e("SendTestActivity", "AuthToken: " + authToken);
        OAuthString = String.format("user=%s\1auth=Bearer %s\1\1", userName, authToken);
        Log.e("SendTestActivity", "non base 64: " + OAuthString);
        if (base64_encode)
            OAuthString = Base64.encodeToString(OAuthString.getBytes(), Base64.DEFAULT);
        Log.e("SendTestActivity", "base 64: " + OAuthString);
        return OAuthString;
    }

    private synchronized void sendMail(String subject, String body, String user, String recipients) {
        try {           
            Properties props = new Properties();
            props.put("mail.smtp.starttls.enable", "true");
            props.put("mail.smtp.starttls.required", "true");
            props.put("mail.smtp.sasl.enable", "false");

            session = Session.getInstance(props);
            session.setDebug(true);

            final URLName unusedUrlName = null;
            SMTPTransport transport = new SMTPTransport(session, unusedUrlName);
            // If the password is non-null, SMTP tries to do AUTH LOGIN.
            final String emptyPassword = null;
            transport.connect("smtp.gmail.com", 587, user, emptyPassword);

            transport.issueCommand("AUTH XOAUTH2 " + GenerateOAuth2String(true),
                    235);

            MimeMessage message = new MimeMessage(session);

            // Set From: header field of the header.
             message.setFrom(new InternetAddress(user));

             // Set To: header field of the header.
             message.addRecipient(Message.RecipientType.TO, new InternetAddress(recipients));

             // Set Subject: header field
             message.setSubject(subject);

             // Now set the actual message
             message.setText(body);

            if (recipients.indexOf(',') > 0)   
                message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipients));   
            else  
                message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipients));   

            Transport.send(message);

            Log.e("SendTestActivity", "email sent");

        } catch (Exception e) {
            Log.e("SendTestActivity", e.getMessage());
        }

    }

is there something wrong with the setup?

also does the \1 in user=%s\1auth=Bearer %s\1\1 a "string" or a "start of heading" character

Bill Shannon · Accepted Answer · 2016-09-02 18:57:16Z

2

You're doing it the hard way. Let JavaMail do it for you.

answered Sep 2, 2016 at 18:57

Bill Shannon

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6 Comments

vims liu Over a year ago

Hi, I am using JavaMail, but it only shows how to connect to read messages through imap, what i am intending to do is send messages through smtp

Bill Shannon Over a year ago

If you follow the link, it explains how you only have to replace "imap" with "smtp" in the property names. Was that not clear?

Bill Shannon Over a year ago

In case you're still confused, this is the send method you want to use.

vims liu Over a year ago

hi the send method requires the password does it mean that the oauth token will be placed in the password section? and yes I am still confused

vims liu Over a year ago

hi, was able to send using the link you gave, I though the password parameter is for the actual password of the user's account, but then when I compare to the Store.connect's method the oauth token is also placed in the password parameter so when I tried to pass the oauth token in the password parameter of Transport.send function it works and my mail account the received the email. thanks very much.

|

Angel Cuenca · Accepted Answer · 2016-09-02 13:50:21Z

0

Did you tried giving permission here:

https://www.google.com/settings/security/lesssecureapps

Some of the errors like that are because you don't have the complete properties, complements with this:

props.put("mail.smtp.auth", "true");
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.host", "smtp.gmail.com");
props.put("mail.smtp.ssl.trust", "smtp.gmail.com");
props.put("mail.smtp.port", "587");

answered Sep 2, 2016 at 13:50

Angel Cuenca

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1 Comment

vims liu Over a year ago

Hi, this is old style and may not be supported in the future, using oauth2 you are not required to turn on lesssecureapps, plus it is more secure, you cannot just let users of your app to allow less secure app, it will make there email vulnerable

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