Server-side Web Programming

Lecture 19: Java Mail

How email works

Sending Client

Mail ClientSoftware

Sending Server

Mail ServerSoftware

Receiving Client

Mail ClientSoftware

Receiving Server

Mail ServerSoftware

SMTP

SMTP

POP/ IMAP

3 protocols

• SMTP: Simple Mail Transfer Protocol– is used to send a message from the mail client

software to your mail server / or from one mail server to another

• POP: Post Office Protocol– transfers all messages from the mail server to the

mail client. POP in version 3: POP3• IMAP: Internet Message Access Protocol

– Is used by web-based mail services such as Hotmail, Yahoo, and Gmail.

– Allows a web browser to read messages that are stored on the mail server. IMAP in version 4: IMAP4

Normal Email Process

• Mail client software converts message to SMTP (or other) format before sending to server

• Common form for usual components of message:– Sender– Recipient(s)– Subject– Text– Etc.

• Mail server sends message in MIME protocol to receiving server– Multipurpose Internet Message Extension

• Mail client software on receiving client accesses using mail client software (possibly different)– POP– IMAP

Java Mail

• Java Mail API is a programming interface that makes it easy for Java developers to write code that automatically sends an email.

• Key idea: Java Mail (or other mail software) must emulate what mail client software does– Create SMTP or other protocol message– Insert required mail components – Connect with sending server and transmit message

• Requires mail classes– Download from www.java.sun.com– Insert mail.jar and activation.jar file into java libraries

• mail. jar: contains the Java classes for the Java Mail API • activation. jar: contains the Java classes for the JavaBean Activation

Framework. These classes are necessary for the JavaMail API to run

How to install the Java Mail API and JavaBeans Activation Framework API

• Locate the download page for the JavaMail API/JavaBeans Activation Framework API on the Java website: www.java.sun.com

• Click on the Download button and follow the instructions

• Save the zip file: javamail-1_4.zip/jaf-1_1.zip to your hard disk

• Extract the files from the zip file• Copy the mail.jar/activation.jar file to the JDK’s

jre\lib\ext directory

Steps in Java Mail

• Create a mail session– Creates email message object

• Set message components– Properties of message object

• Set addresses– Can be list for group of recipients

• Send message– May need to identify self to server

• Will need mail libraries<%@ page import="javax.mail.*, javax.mail.internet.*, java.util.*"%>

Creating an Email Session

• Create a Properties object to store information:– Generic Java class to store attribute/value pairs

– Property props = new Properties();

• Specify the sending server:– props.put(“mail.smtp.host”, URL of mail server);

• Create a new session object from those properties:– Session s = Session.getDefaultInstance(props);

• Create new MimeMessage object from session– MimeMessage message = new MimeMessage(s);

Common properties

• mail.transport.protocol: specifies the protocol that’s used for the session

• mail.smtp.host: specifies the host computer for SMTP server

• mail.smtp.port: specifies the port that the SMTP server is using

• mail.smtp.auth: specifies whether authentication is required to log in to the SMTP server

• mail.smtp.quitwait: this property can be set to false to prevent an SSLException from occurring when you attempt to connect to a Gmail SMTP server

• To set the properties of Properties object, you can use the put method to specify of a property name and value

• The static getDefaultInstance method of the Session class returns the default Session object for the application

• The setDebug method of the Session object can be used to print debugging information about the session to a log file

• If you change the properties for a Session object, you must restart Tomcat before the changes take effect

• If the Java application is running on the same computer as the SMTP server, you can use the localhost keyword to specify the SMTP host.

Setting Message Components

• Set the subject:– message.setSubject(“subject”);

• Set the message text:– message.setText(“Thanks for your order!”);

//”text/plain”

• Could also be html or other types– Will need to specify MIME type

String response = “<html><head><title>Reciept</title</head><body><h3>Thank you for your order!</h3>”;

message.setContent(response, “text/html”);

Setting Addresses

• Use setRecipient method– Specify internet address of recipient

• Must use InternetAddress class• InternetAddress constructor requires email address, can also optionally

give name

– Specify TO, CC, or BCC

– Can add multiple recipients

Message.setRecipient(Message.RecipientType.TO, new InternetAddress(“slade@quarry.com”));

Message.setRecipient(Message.RecipientType.CC,new InternetAddress(barney@aolrock.com, “Barney Rubble”));

Setting Addresses• Address can also be a list

– Good for mailing lists– Array of type Address

• Use setRecipients methodAddress[] list = new Address[size of mailing list];for (int i = 0; i < size of mailing list; i++) { list[i] = get next address for file; }Message.setRecipients(Message.RecipientType.TO, list);• Use addRecipient methodMessage.addRecipient(Message.RecipientType.TO,

new InternetAddress(“slade@quarry.com”) )Using addRecipient/addRecipients to add email addresses to any

existing addresses for a message

Sending Messages

• Simple method:Transport.send(message);

• More complex method if server requires authentication:– Create Transport object from sessions

Transport t = session.getTransport();– Connect to server with name and password

t.connect(“your name”, “your password”);– Send the message

t.sendMessage(message, message.getAllRecipients());