Java Training
Introduction to Java Mail
What is JavaMail? -1
JavaMail is an API for sending and receiving email using
Java. The current version is 1.3.1 and can be downloaded
from Sun's website at:
http://java.sun.com/products/javamail/
Possible uses:
Send email from web pages using servlets
Create a GUI email client
Send email from Java stored procedures
Send email from any type of Java application
Spam your friends and enemies! (read email addresses
from a database, write a for () loop, and away the emails
go!)
What is JavaMail? -2
To send JavaMail, you'll need to add at least two JAR files
from Sun to your classpath (placing them in a lib directory
may be a good idea)
activation.jar
mail.jar
(Note: You can download these files from the Java Zone)
For more complex emailing tasks (like receiving or
managing pop3 or imap mail servers), you'll need to
download additional files like pop3.jar and imap.jar.
You will also need access to a mail server and possibly a
username/password for that mail server
How Does Email Work?
In general, each internet domain has an email server.
When you send out an email
Your email client program sends the message to your
email server
Your email server contacts the addressee's email server
using the SMTP (simple mail transfer protocol)
Your email server verifies that the addressee's user
name is valid
Your email server then transfers the email to the
addressee's email server
When the addressee logs into his email server (using his
email client program), he gets his email
Mail Servers (sendmail)-1
sendmail is the most commonly used mail server in the
world, as it generally comes free with Unix and Linux
installations
very powerful and flexible. Supports POP3 and IMAP
well documented (lots of books on setting up sendmail)
long track record (first version appeared in early '80s)
tedious to set up (lots of cryptic configuration files)
free
www.sendmail.org
Mail Servers (qmail)-2
qmail is probably the most popular alternative to sendmail
in the UNIX world
perhaps more secure than sendmail (at least older
versions of sendmail)
Easier to set up and administer than sendmail
pretty good documentation (several books written on
qmail in the past few years)
free
http://www.qmail.org/top.html
Mail Servers (MS Exchange)-2
MS Exchange is widely used in the Windows world,
especially in corporate environments that use MS Office
(and hence MS Outlook)
Expensive
Integrated into MS Active Directory
GUI administration tools are easier to learn for Windows
people
MS Outlook is a powerful and slick email program that will
work with Exchange, sendmail, or qmail. It does, however,
have a history of security vulnerabilities and some
organizations refuse to use it because of that.
POP3, IMAP, MAPI -1
Currently, the most popular protocols are
POP3 (Post Office Protocol, version 3)
IMAP (Internet Message Access Protocol)
MAPI (Messaging Application Programming Interface--
Microsoft Windows email interface)
POP3
POP3 is the oldest and most widely used. It was designed
to support offline mail processing.
Mail is delivered to a server and a user's computer runs
a mail client program to download any new mail
Once messages are delivered, they are generally
deleted from the mail server
This minimizes disk space requirements for mail server,
but ties the mail to a particular machine. If user goes to
another computer, he can't access his mail
POP3 has limited support for reading mail online (and
leaving the mail on the mail server)
Simpler protocol than IMAP makes it easier to
implement. More POP3 mail clients available
IMAP
IMAP
Developed at University of Washington
Primarily used to access mail and leave it on the mail
server. This allows users to access their mail from any
computer
Requires more disk space to store email messages
Can work in "offline" mode like POP3
Easy to manage multiple mailboxes
Supports tagging emails with flags like "read", "deleted",
"answered", etc.
MAPI
MAPI
Set of C functions (API) developed by Microsoft and
supported in MS Exchange/Outlook
Also supported by Eudora Mail
For more info, type the following search string in Google:
"MAPI site:msdn.microsoft.com"
Apache James Mail Server
Apache has a free mail server called James
Supports POP3, SMTP, and NNTP
Download the binary file
.ZIP version (for Windows)
.TAR version (for Linux)
Uncompress it and then run “run.bat” (Windows) or “run.sh”
(Linux) to start the mail server
Download from here:
http://james.apache.org/download.cgi
NOAA Mail Server
You can use ESRL/NOAA’s email server
email.boulder.noaa.gov
mailProperties.setProperty("mail.smtp.host","email.boulder.noaa.gov");
This will work IF you send emails to @noaa.gov email
addresses (like
[email protected])
When I tried to send an email to
[email protected] I got
this error message
Invalid Address
Relaying not allowed:
[email protected]
Using JavaMail -1
Once you have a mail server you can use (either James or
another mail server), you can send emails through it by
using JavaMail
In general, to send a plain text email using JavaMail, you do
the following:
Get a mail session instance
Create a MimeMessage object (passing in the mail
session instance into the constructor)
Set the MimeMessage object's properties (like the
toAddress, fromAddress, message, etc.)
Send the message
Getting a Mail Session
Get a mail session for the James mail server. If James is
running on your own computer, your mail.smtp.host is
localhost.
If your mail server is a remote computer, it might be
something like “mailgate.fsl.noaa.gov”
Get a mail session for the James mail server
private Session getMailSession() throws Exception
{
Properties mailProperties = new Properties();
mailProperties.setProperty("mail.transport.protocol",
"smtp");
mailProperties.setProperty("mail.smtp.host",
"localhost");
return Session.getInstance(mailProperties, null);
}
Plain Text Email Example
Next, send your email using the mail session
MimeMessage msg = new MimeMessage(getMailSession());
msg.setFrom(new InternetAddress("
[email protected]"));
msg.addRecipient(Message.RecipientType.TO,
new InternetAddress("
[email protected]"));
msg.setSubject("RE: Oracle vs SQL Server");
msg.setText("SQL Server is better than Oracle");
Transport.send(msg);
Exceptions and imports
Your code which sends an email will need to catch the
following checked exceptions:
Exception
MessagingException
AddressException
You should import the following packages:
import javax.mail.*;
import javax.mail.internet.*;
HTML Email
You can also send HTML email with JavaMail. HTML email
can be used to
Use different size fonts
imbed images into your email
Use different colored text, bold, italic, etc.
HTML Email
With HTML email,
you set the mime message content type to "text/html"
call the setContent() method to set your html content
It helps to know a little HTML!
Mail Security
Virtually all mail servers require a username and password
to receive email
Some mail servers require a username and password to
send an email (by default, James does not).
This prevents spammers from hijacking the mail server
to send unauthorized email
JavaMail supports this username/password authorization
and authentication
To implement this, you get a transport object from the
mail session and call the connect() method with the mail
host, username, and password
See next slide for code example