Sending emails using Java Mail and Google Mail account

Requirements:

• installed Java (description here)
• installed and configured Eclipse (description here)
• valid Google Mail account

You will learn:

• how to send e-mails from Java application using Java Mail and Google Mail account.

Sometimes You need to send an email from Your Java application. In order to do this You have to use valid e-mail account, and You have to know the address of SMTP server for this account. And of course You have to write some code which will connect to the SMTP server (using Your account credentials) and then create and send email. A Google Mail account will be used as an example.

Step 1: create clean Java Eclipse Project

Step 2: download  JavaMail API 1.4.4 (javamail_1_4_4.zip) from here.

After downloading JavaMail, extract it and go into its /lib folder. Copy all .jar files from that directory into Your project and add them to the build path.

Step 3: write a simple code for sending email using Google Mail. You can use TLS or SSL connection to Google SMTP server.

a) using TLS connection to SMTP server:

// ...
import java.util.Properties;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
// ...
Properties propsTLS = new Properties();
propsTLS.put("mail.transport.protocol", "smtp");
propsTLS.put("mail.smtp.host", "smtp.gmail.com");
propsTLS.put("mail.smtp.auth", "true");
propsTLS.put("mail.smtp.starttls.enable", "true"); // GMail requires STARTTLS

Session sessionTLS = Session.getInstance(propsTLS);
sessionTLS.setDebug(true);

Message messageTLS = new MimeMessage(sessionTLS);
messageTLS.setFrom(new InternetAddress("random_sender_4568744122@gmail.com", "John Smith"));
messageTLS.setRecipients(Message.RecipientType.TO, InternetAddress.parse("random_recipient_4568744122@gmail.com")); // real recipient
messageTLS.setSubject("Test mail using TLS");
messageTLS.setText("This is test email sent to Your account using TLS.");

Transport transportTLS = sessionTLS.getTransport();
transportTLS.connect("smtp.gmail.com", 587, "random_sender_4568744122@gmail.com", "sender_account_pass"); // account used
transportTLS.sendMessage(messageTLS, messageTLS.getAllRecipients());
transportTLS.close();

b) using SSL connection to SMTP server:

// ...
import java.util.Properties;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
// ...
Properties propsSSL = new Properties();
propsSSL.put("mail.transport.protocol", "smtps");
propsSSL.put("mail.smtps.host", "smtp.gmail.com");
propsSSL.put("mail.smtps.auth", "true");

Session sessionSSL = Session.getInstance(propsSSL);
sessionSSL.setDebug(true);

Message messageSSL = new MimeMessage(sessionSSL);
messageSSL.setFrom(new InternetAddress("random_sender_4568744122@gmail.com", "John Smith"));
messageSSL.setRecipients(Message.RecipientType.TO, InternetAddress.parse("random_recipient_4568744122@gmail.com")); // real recipient
messageSSL.setSubject("Test mail using SSL");
messageSSL.setText("This is test email sent to Your account using SSL.");

Transport transportSSL = sessionSSL.getTransport();
transportSSL.connect("smtp.gmail.com", 465, "random_sender_4568744122@gmail.com", "sender_account_pass"); // account used
transportSSL.sendMessage(messageSSL, messageSSL.getAllRecipients());
transportSSL.close();

Note: in both cases You for the connect() method, You have to pass a real login and password of the Google Mail account used. The main differences between those two methods are: different protocol (smtp for TLS and smtps for SSL), different ports (587 for TLS and 465 for SSL). In addition TLS requires STARTTLS.

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Download source files:

Note: make sure that Java and Eclipse are properly installed and configured for running the project (additional configuration may be required if different directories are used).


Eclipse complete sample project is here (with all required libraries).

SSL in Tomcat under Eclipse (part 2 - certificate from CA)

Requirements:

• You should be able to generate self signed SSL certificate and integrate it into Tomcat, as described in previous post.

You will learn:

• how to obtain and install a real SSL certificate from well known Certificate Authority (CA)

In the previous post I described the complete procedure of generating self signed SSL certificate and integrating it into Tomcat. In this post I would like to focus on the example with real certificate obtained from CA - I will use Thawte as example.

Note: let's assume that You created an application which is going to be visible under the following URL: http://www.myapp.com.

Step 1: generating self signed certificate for domain www.myapp.com.

This is exactly the same step to step 1 in previous post. You have to execute the following command:

keytool -genkey -alias myappcert -keyalg RSA -keystore myapp.keystore

Step 2: Generate Certificate Signing Request (CSR).

You have to generate a special request, which will be send to the CA. You have to execute command:

keytool -certreq -keyalg RSA -alias myappcert -file certreq.csr -keystore myapp.keystore

Generated request is saved as a certreq.csr file, which will be send to CA. CA will use this file to generate certificate signed by them.

Important: You have to use exactly the same alias (in this example: myappcert) for step 1 and step 2.

Step 3: Getting certificate from CA.

Usually certificate are delivered in PKCS#7 or X.509 format. For the first one, the file with certificate will have .p7b extension, for the second one - .cer. Sometimes You can get such certificate also by email as a pure text - for the X.509 format, certificate will be placed between tags -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----, for PKCS#7 certificate will be placed between tags -----BEGIN PKCS7----- and -----END PKCS7-----. Then You have to copy the certificate content (including those begin/end tags!) and save this as a .cer or .p7b file (You can use Notepad for that). Now You are ready to import Your signed certificate.

Step 4: importing signed certificate.

a) as a .p7b (PKCS#7) format:

Acording to the Thawte, when You obtained Your certificate as a .p7b file, You need only one command to import and install this certificate in Your keystore:

keytool -import -alias myappcert -trustcacerts -file signed_cert.p7b  -keystore myapp.keystore

where signed_cert.p7b is a signed certificate obtained from CA.

b) as a .cer (X.509) format:

According to the Thawte, when You obtained Your certificate as .cer file,  You need to download Primary and Secondary Intermediate CAs and import them. They are delivered as .p7b format (i.e. intermediate.p7b). I should import them first, using command:

keytool -import -trustcacerts -alias intermediatecerts  -file intermediate.p7b -keystore myapp.keystore

and then import my certificate (it is in .cer file signed_cert.cer) using this command:

keytool -import -trustcacerts -alias myappcert -file signed_cert.cer -keystore myapp.keystore

where signed_cert.cer is a signed certificate obtained from CA.

Problem and workaround:

Both above ways seems to be simple, but... when I was buying some time ago a web SSL certificate from Thawte, I receive certificate as a pure text in e-mail. Certificate was in X.509 format (I had tags ----BEGIN/END CERTIFICATE-----). I created a signed_cert.cer file from that e-mail content. Then I tried to install intermediate certificates like it was described in Thawte documentation. Unfortunately it didn't work. The first command for importing intermediate certificates failed with error:

keytool error: java.lang.Exception: Input not an X.509 certificate

It seems that keytool does not work with .p7b format (I used JDK 1.6.0_16), so I expect that even if I get my certificate as .p7b file (complete, without need to import intermediate certificates as in a) subpoint) it will also not work. I took a .p7b file with intermediate certificates, opened it under Windows, and for each certificate found inside i exported it as a X.509 DER certificate, giving each file .cer extension. So I had three .cer (X.509) files: signed_cert.cer, thawte_primary.cer, thawte_secondary.cer. Now I had to import intermediate certificates and after that import my signed certificate with those commands:

keytool -import -trustcacerts -alias primary -file thawte_primary.cer -keystore myapp.keystore
keytool -import -trustcacerts -alias secondary -file thawte_secondary.cer.cer -keystore myapp.keystore

keytool -import -trustcacerts -alias myappcert -file signed_cert.cer -keystore myapp.keystore

Now import was OK. So the general workaround rule (if there are any troubles) is: get all needed certificates in X.509 form, import intermediate certificates (if any required) and import Your signed certificate at the end.

Important: You have to use exactly the same alias (in this example: myappcert) like You used in step 1 and step 2, except for importing intermediate certificates - You can use whatever alias You like.

Step 5: copy Your myapp.keystore file into Tomcat's /conf directory

Step 6: modify Tomcat configuration to use SSL certificate

It is exactly the same as step 3 in previous post.

That's all.

SSL in Tomcat under Eclipse (part 1 - self signed certificate)

Requirements:

• installed Java (description here)
• installed and configured Eclipse (description here)
• installed and configured Tomcat for the Eclipse (description here)

You will learn:

• how to set up Tomcat for SSL connection using self signed certificate under Eclipse

When You want to secure Your application SSL is the most natural choice. In order to make Your application be recognized as trusted by browser, You can by a buy a certificate from well known certificate authority (CA), which will be generated for the domain Your application uses. If You do not care about being recognized as trusted service, but instead You just want to encrypt the data exchanged between server and client's browser, You can use Your own self signed SSL certificate. In this post I will show how to generate such SSL certificate and how to set up Tomcat (from the Eclipse level) to use generated certificate.

Note: let's assume that You created an application which is going to be visible under the following URL: http://www.myapp.com.

Step 1: generating self signed certificate for domain www.myapp.com.

Go into Your Java bin directory (i.e C:\Development\Java\bin). Then open Windows console (under Windows Vista/7 open the console with Administrator right) and type in command:

keytool -genkey -alias myappcert -keyalg RSA -keystore myapp.keystore

where myappcert is the name of the certificate being generated and myapp.keystore is a file where certificate will be stored. You will be asked about the password for created the myapp.keystore file. Type in "mypass", press Enter and type it again and press Enter again. Then You will be asked for some details about You:

Please note that for the first question about first and last name I gave answer www.myapp.com. This is very important - this name (known as CN - Common Name) will be used for the checking if certificate on the page we visit was generated for the same URL which we typed in in the browser.

At the end You will be asked for the password for the newly created certificate. The password must be the same as one used for myapp.keystore file ("mypass"). Do not type antyhing, just press Enter to use the same password. Your myapp.keystore file containing myappcert certificate is ready.

Step 2: copy Your myapp.keystore file into Tomcat's /conf directory

Step 3:  modify Tomcat configuration to use SSL certificate.

Make sure that Your Tomcat is configured with Eclipse and works OK without SSL (start Tomcat from Eclipse and type in http://localhost:8080 in the browser). Stop Tomcat if it is running. Then open server.xml file form the "Servers" view:

and locate default element for standard HTTP connections (marked red). Then add additional element for the SSL connection (next to existing one):

<Connector
        SSLEnabled="true"
        clientAuth="false"
        keyAlias="myappcert"
        keystoreFile="conf/myapp.keystore"
        keystorePass="mypass"
        maxThreads="200"
        port="8081"
        scheme="https"
        secure="true"
        sslProtocol="TLS"
 /> 

Please note that next to some specific SSL settings, we set the location of the keystore file, the password for that file and certificate name to be use. SSL connection uses port 8081, where normal HTTP connection

uses port 8080.

Note 1: all modification of server.xml file were done from Eclipse level, using "Servers" view. If You want to use Eclipse WTP for starting Tomcat (like I do so far) You can't edit this file from elsewhere. Eclipse WTP overrides original Tomcat configuration files by files visible under "Servers" - changes done outside Eclipse will not be visible for WTP.

Note 2: I added element specific for SSL next to existing element for standard non encrypted HTTPS connections. This is second issue directly connected with Eclipse WTP - when You remove standard connector for HTTP, Eclipse will close Tomcat after a time set in "Timeouts" section in the Tomcat settings:

Some people try to extend the timeout time into long period, but still after this period Eclipse kills Tomcat process, as if Tomcat was not properly started in the required time. Unfortunately there is no way to set timeout into ifinite time - the only way to fix this under WTP is to leave standard HTTP element in Tomcat's server.xml file.

Step 4: that's all. Tomcat is configured to work with SSL. 

Try to enter the URL: https://localhost:8081. If You see Tomcat's page, everything works OK (You can see certificate warning - You Need to add security exception for that certificate). Of course You can still open the same Tomcat page by standard HTTP (You have two elements), just enter http://localhost:8080 URL.