added example code for Java mail (#4101)

core-java/pom.xml

@@ -235,6 +235,11 @@
            <artifactId>h2</artifactId>
            <version>1.4.197</version>
         </dependency>
+        <dependency>
+            <groupId>javax.mail</groupId>
+            <artifactId>mail</artifactId>
+            <version>1.5.0-b01</version>
+        </dependency>
     </dependencies>
 
     <build>

core-java/src/main/java/com/baeldung/mail/EmailService.java

@@ -0,0 +1,80 @@
+package com.baeldung.mail;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.util.Properties;
+import javax.mail.*;
+import javax.mail.internet.InternetAddress;
+import javax.mail.internet.MimeBodyPart;
+import javax.mail.internet.MimeMessage;
+import javax.mail.internet.MimeMultipart;
+
+public class EmailService {
+
+    private String host = "";
+    private int port = 0;
+    private String username = "";
+    private String password = "";
+
+
+    public EmailService(String host, int port, String username, String password) {
+
+        this.host = host;
+        this.port = port;
+        this.username = username;
+        this.password = password;
+
+        sendMail();
+    }
+
+    private void sendMail() {
+
+        Properties prop = new Properties();
+        prop.put("mail.smtp.auth", true);
+        prop.put("mail.smtp.starttls.enable", "true");
+        prop.put("mail.smtp.host", host);
+        prop.put("mail.smtp.port", port);
+        prop.put("mail.smtp.ssl.trust", host);
+
+        Session session = Session.getInstance(prop, new Authenticator() {
+            @Override
+            protected PasswordAuthentication getPasswordAuthentication() {
+                return new PasswordAuthentication(username, password);
+            }
+        });
+
+        try {
+
+                Message message = new MimeMessage(session);
+                message.setFrom(new InternetAddress("from@gmail.com"));
+                message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("to@gmail.com"));
+                message.setSubject("Mail Subject");
+
+                String msg = "This is my first email using JavaMailer";
+
+                MimeBodyPart mimeBodyPart = new MimeBodyPart();
+                mimeBodyPart.setContent(msg, "text/html");
+
+                MimeBodyPart attachmentBodyPart = new MimeBodyPart();
+                attachmentBodyPart.attachFile(new File("pom.xml"));
+
+                Multipart multipart = new MimeMultipart();
+                multipart.addBodyPart(mimeBodyPart);
+                multipart.addBodyPart(attachmentBodyPart);
+
+                message.setContent(multipart);
+
+                Transport.send(message);
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static void main(String ... args) {
+        new EmailService("smtp.mailtrap.io", 25, "87ba3d9555fae8", "91cb4379af43ed");
+    }
+
+}