Nagarajan S R Nagarajan S R - 6 months ago 180
Java Question

Unable to send an email using SMTP (Getting javax.mail.MessagingException: Could not convert socket to TLS;)

I have written the following code for sending email using javamail API through SMTP as TLS as SSL is not supported but I ended up with the following exception. Please see my code below. I have used debugging mode and below the code you can find the exception as well.

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendMailTLS {

public static void main(String[] args) {

final String username = "---------@mydomain.com";
final String password = "***********";

Properties props = new Properties();
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.host", "mail.mydomain.com");
props.put("mail.smtp.debug", "true");
props.put("mail.smtp.port", "587");

Session session = Session.getInstance(props,
new javax.mail.Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username, password);
}
});
session.setDebug(true);

try {

Message message = new MimeMessage(session);
message.setFrom(new
InternetAddress("---------@mydomain.com"));
message.setRecipients(Message.RecipientType.TO,
InternetAddress.parse("---------@mydomain.com"));
message.setSubject("Testing Subject");
message.setText("Dear Mail Crawler,"
+ "\n\n No spam to my email, please!");

Transport.send(message);

System.out.println("Done");

} catch (MessagingException e) {
throw new RuntimeException(e);
}
}
}


Exception trace

DEBUG: setDebug: JavaMail version 1.4.5
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "mail.mydomain.com", port 587, isSSL false
220-cpanel35.per.syra.net.au ESMTP Exim 4.80 #2 Fri, 05 Oct 2012 17:28:56 +0800
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
DEBUG SMTP: connected to host "mail.mydomain.com", port: 587

EHLO xxxxxx.xxxxx.com
250-cpanel35.per.syra.net.au Hello xxxx.xxxxx.com [xx.xx.xx.xxx]i
250-SIZE 52428800
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN
250-STARTTLS
250 HELP
DEBUG SMTP: Found extension "SIZE", arg "52428800"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "AUTH", arg "PLAIN LOGIN"
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "HELP", arg ""
STARTTLS
220 TLS go ahead
Exception in thread "main" java.lang.RuntimeException: javax.mail.MessagingException: Could not convert socket to TLS;
nested exception is:
javax.net.ssl.SSLException: java.lang.RuntimeException: Could not generate DH keypair
at SendMailTLS.main(SendMailTLS.java:52)
Caused by: javax.mail.MessagingException: Could not convert socket to TLS;
nested exception is:
javax.net.ssl.SSLException: java.lang.RuntimeException: Could not generate DH keypair
at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:1918)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:652)
at javax.mail.Service.connect(Service.java:317)
at javax.mail.Service.connect(Service.java:176)
at javax.mail.Service.connect(Service.java:125)
at javax.mail.Transport.send0(Transport.java:194)
at javax.mail.Transport.send(Transport.java:124)
at SendMailTLS.main(SendMailTLS.java:47)
Caused by: javax.net.ssl.SSLException: java.lang.RuntimeException: Could not generate DH keypair
at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1868)
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1826)
at sun.security.ssl.SSLSocketImpl.handleException(SSLSocketImpl.java:1809)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1328)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1305)
at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:548)
at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:485)
at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:1913)
... 7 more
Caused by: java.lang.RuntimeException: Could not generate DH keypair
at sun.security.ssl.DHCrypt.<init>(DHCrypt.java:123)
at sun.security.ssl.ClientHandshaker.serverKeyExchange(ClientHandshaker.java:618)
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:202)
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:868)
at sun.security.ssl.Handshaker.process_record(Handshaker.java:804)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:998)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1294)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1321)
... 11 more
Caused by: java.security.InvalidAlgorithmParameterException: Prime size must be multiple of 64, and can only range from 512 to 1024 (inclusive)
at com.sun.crypto.provider.DHKeyPairGenerator.initialize(DHKeyPairGenerator.java:120)
at java.security.KeyPairGenerator$Delegate.initialize(KeyPairGenerator.java:658)
at sun.security.ssl.DHCrypt.<init>(DHCrypt.java:117)
... 18 more


Can anyone help me debug this? Thanks in advance!

Answer

I resolved this issue by just commenting the below property

props.put("mail.smtp.starttls.enable", "true"); 

and the code got executed with no errors or warning or simply delete this line from the above source code. It is working like a charm till date.

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