Android javamail 501 5.5.4 Invalid argument

Question

I am trying to send email using Mailgun. According to mailgun, I am using the following code :

public static void TestMail() throws Exception
{

            Properties props = System.getProperties();
            props.put("mail.smtps.host","smtp.mailgun.org");
            props.put("mail.debug", "true");
            props.put("mail.verbose", "true");
            props.put("mail.smtps.auth","true");
            Session session = Session.getInstance(props, null);
            Message msg = new MimeMessage(session);
            msg.setFrom(new InternetAddress("fromaddress@gmail.com"));
            msg.setRecipients(Message.RecipientType.TO,
                    InternetAddress.parse("toaddress@gmail.com", false));
            msg.setSubject("Hello");
            msg.setText("Testing some Mailgun awesomness");
            msg.setSentDate(new Date());
            SMTPTransport t =
                    (SMTPTransport)session.getTransport("smtps");
            t.setStartTLS(true);
            t.connect("smtp.mailgun.com", "postmaster@sandbox86837*********.mailgun.org", "b071d**********");
            t.sendMessage(msg, msg.getAllRecipients());
            System.out.println("Response: " + t.getLastServerResponse());
            t.close();


}

I am using the javamail api downloaded from : https://code.google.com/p/javamail-android/downloads/list

NOW IN THE DEBUG FOLLOWING INFORMATION IS DISPLAYED :

DEBUG: JavaMail version 1.4.1
DEBUG: not loading file: /system/lib/javamail.providers
DEBUG: java.io.FileNotFoundException: /system/lib/javamail.providers: open failed: ENOENT (No such file or directory)
DEBUG: not loading resource: /META-INF/javamail.providers
 DEBUG: not loading resource: /META-INF/javamail.default.providers
DEBUG: failed to load any providers, using defaults

DEBUG: not loading resource: /META-INF/javamail.default.address.map
DEBUG: !anyLoaded
DEBUG: not loading resource: /META-INF/javamail.address.map
DEBUG: not loading file: /system/lib/javamail.address.map
 DEBUG: java.io.FileNotFoundException: /system/lib/javamail.address.map: open failed: ENOENT (No such file or directory)
DEBUG: failed to load address map, using defaults
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Sun Microsystems, Inc.,1.4.1]
DEBUG SMTP: useEhlo true, useAuth true


DEBUG SMTP: trying to connect to host "smtp.mailgun.com", port 465, isSSL true
220 ak47 ESMTP ready
DEBUG SMTP: connected to host "smtp.mailgun.com", port: 465
EHLO
501 5.5.4 Invalid argument
 HELO
501 5.5.4 Invalid argument

I have no idea what this error means ? When I googled no one pointed the exact cause of the error or the reason. It could be ssl or my system is missing some java library ?? Or the java lib that I downloaded is not correct.

But as you see in the debug, it was able to connect successfully to smtp.mailgun.com. Then why this error ? Please please help me.

Thanks

Answer 1

The server to which you are connecting is requiring that the argument to the HELO or EHLO be either a hostname or an IP address.

Your code does not seem to be sending either.

The RFC (RFC2821 page 29) seems to be somewhat ambiguous...

...the client SHOULD send an IP address if no hostname is available

where the word MUST would have been used if this was a requirement. But the syntax description of HELO/EHLO seems to indicate the argument is required.

Also in section 3.6 (on Domains):

• The domain name given in the EHLO command MUST BE either a primary host name (a domain name that resolves to an A RR) or, if the host has no name, an address literal as described in section 4.1.1.1.

Answer 2

So, finally I was able to send mail using MAILGUN. But I had to drop the idea of using JAVAMAIL for sending as I could not solve this issue of invalid argument.

Retrofit provides a class for sending email using MAILGUN.I am posting the code I used here for anyone facing problem with Mailgun :

public interface SendMailApi {
@Headers({ACCEPT_JSON_HEADER})
@FormUrlEncoded
@POST("/messages")
void authUser(
        @Header("Authorization") String authorizationHeader,
        @Field("from") String from,
        @Field("to") String to,
        @Field("subject") String subject,
        @Field("text") String text,
        Callback<MailGunResponse> cb
);

}

public void sendMail(String to, String subject, String msg,      Callback<MailGunResponse> cb){
String from = "test <test@address.com>";
String clientIdAndSecret = "api" + ":" + "key-*******";
String authorizationHeader = BASIC + " " +     Base64.encodeToString(clientIdAndSecret.getBytes(), Base64.NO_WRAP);
sendMailApi.authUser(authorizationHeader,from, to, subject, msg, cb);
}

public MailGun() {
RestAdapter restAdapter = getAuthAdapter();
sendMailApi = restAdapter.create(SendMailApi.class);
}

private RestAdapter getAuthAdapter(){
RestAdapter.LogLevel logLevel = RestAdapter.LogLevel.FULL;
if(DEBUG)logLevel = RestAdapter.LogLevel.FULL;
return new RestAdapter.Builder()
        .setEndpoint(ENDPOINT)
        .setConverter(new GsonConverter(new Gson()))
        .setLogLevel(logLevel)
        .build();
}

Answer 3

I suggest you to use the RESTful API instead of the SMTP legacy backend. You can use the Jersey library and the official documentation of Mailgun which provides accurate examples.

Also, and a big disclaimer, I've recently published a Java Mailgun library to ease with that. See this answer.