 | Chapter 14 Email Connectivity |  |
The Mail modules operate at a higher level than the Net modules, interacting with external mail packages such as mail, mailx, sendmail, or a POP3 server in the case of POP3Client. This section describes some of the MailTools modules, Mail::Folder, and Mail::POP3Client.
The Mail::Mailer module interacts with external mail programs. When you use Mail::Mailer or create a new Mail::Mailer object, you can specify which mail program you want your program to talk to:
Another way to specify the mailer is:use Mail::Mailer qw(mail);
whereuse Mail::Mailer; $type = 'sendmail'; $mailprog = Mail::Mailer->new($type);
$type is the mail program. Once you've created a new object,
use the open
function to send the message headers to the mail program as a hash
of key/value pairs, where each key represents a header type,
and where the value is the value of that header:
# mail headers to use in the message
%headers = (
'To' => 'you@mail.somename.com',
'From' => 'me@mail.somename.com',
'Subject' => 'working?'
);Once %headers has been defined, it is
passed to open:
You then send the body of the message to the mail program:$mailprog->open(\%headers);
Now, close the program when the message is finished:print $mailprog "This is the message body.\n";
A practical example of using Mail::Mailer might be a command-line-driven application that works much like the Unix mail program, either reading STDIN until EOF or mailing a file specified on the command line.$mailprog->close;
Mail::Mailer uses the environment variable PERL_MAILERS to augment or modify the built-in mailer selection. PERL_MAILERS is specified in the following format:
The possible types are listed for the"type1:mailbinary1;mailbinary2;...:type2:mailbinaryX;...:..."
new method below.The following methods are defined in Mail::Mailer:
Mail::Send is built on top of Mail::Mailer, which means that you can
also choose the mail program that sends the mail. Mail::Send has
implemented the methods to, cc, bcc, and subject
to replace the %headers hash used in Mail::Mailer.
Mail::Send uses the open method to open the mail program for
output; it is built on Mail::Mailer's new method, so that:
# Start mailer and output headers
$fh = $msg->open('sendmail');# use sendmail for mailing
$mailer = Mail::Mailer->new('sendmail)';Mail::Send also provides the set and add
functions, which assign a value to a header tag and append a value
to a header tag, respectively. The set function takes
two arguments - a header tag and a value - and is used like this:
Therefore, to address a message to you@mail.somename.com:$msg->set($scalar, @array);
$msg->set('To', 'you@mail.somename.com');To header to you@mail.somename.com;
however, the following
sets the To header to postmaster@mail.somename.com and
you@mail.somename.com, because they represent an array of values.
$msg->set('To', ('you@mail.somename.com', 'postmaster@mail.somename.com'));set function as follows to add multiple values to a header value:
$msg->set('To', 'you@mail.somename.com');
$msg->set('To', 'someone@their.mailaddress.com');set doesn't append information from one call to another, and the
example above would send the mail only to someone@their.mailaddress.com.
To append a name to the To header, use the add method. For
example:
$msg->add('To', 'you@mail.somename.com');
$msg->add('To', 'someone@their.mailaddress.com');The following methods are defined for Mail::Send:
Once you've begun downloading and reading your mail from a POP server, you might want to save or categorize your messages into folders, which allow you to add, delete, save, and move messages easily. You can do this with Mail::Folder, which was written by Kevin Johnson as an object-oriented, folder-independent interface to mail folders. Mail::Folder supports a number of mailbox formats with the following interfaces:
A folder interface somewhat similar to MH.
An interface to maildir folders.
Standard Unix mailbox format.
The beginnings of an interface to NNTP; not all the methods are implemented yet.
If you are interested in writing a folder interface, see the documentation for the module. The documentation explains the concepts and issues involved, and describes some of the methods you may need to override.
The following methods are defined for Mail::Folder:
Mail::Internet implements a number of helpful functions for manipulating
a mail message. These include body, print_header, and head.
Mail::Internet is built on top of Mail::Header, which parses the header of an
email message, and it inherits the Mail::Header constructor
style that requires a file descriptor or reference to an array be used. For
example:
reads a mail message from STDIN (using a reference to an array). The following example reads a mail message from a filehandle, FILE.@lines = <STDIN>; $mi_obj = new Mail::Internet([@lines]);
Theopen(FILE, "/home/nvp/Mail/nvp"); $mi_obj = new Mail::Internet(\*FILE); close(FILE);
print_header function outputs the header of a message to a file
descriptor; the default is STDOUT.
The above example might output:open(FILE, "/home/nvp/Mail/nvp"); $mi_obj = new Mail::Internet(\*FILE); close(FILE); $mi_obj->print_header(\*STDOUT);
From nvp Mon Jun 9 00:11:10 1997
Received: (from nvp@localhost) by mail.somename.com (8.8/8.8) id
AAA03248 for nvp; Mon, 9 Jun 1997 00:11:09 -0500 (EST)
Date: Mon, 9 Jun 1997 00:11:09 -0500 (EST)
From: "Nathan V. Patwardhan" <nvp>
Message-Id: <199706090511.AAA03248@mail.somename.com>
To: nvp
Subject: pop test
X-Status:
X-Uid: 1
Status: ROprint_body also takes a file descriptor as an argument, but only
outputs the body of the message, whereas the print function outputs an
entire message.Mail::Address parses RFC 822-compliant mail addresses of the form:
For example, under RFC 822, an address might be represented as:"Full Name or Phrase" <username@host> (Comment Area)
or:"Nathan V. Patwardhan" <nvp@mail.somename.com> (No Comment)
The Mail::Address constructor parses an email address into three parts based on the categories shown above:"Nathan V. Patwardhan" <nvp@mail.somename.com>
$addr = Mail::Address->new("Full Name or Phrase",
"username@host",
"(Comment Area)");phrase, address, comment, format, name,
host, and user. The phrase, address, and comment
functions represent the first, second,
and third entities that were passed to the Mail::Address constructor, where
the phrase function:
outputs:print $addr->phrase();
TheNathan V. Patwardhan
address function:
outputs:print $addr->address();
And thenvp@mail.somename.com
comment function:
outputs:print $addr->comment();
A real mail address can be "unmangled," or parsed from its user@somehost.com format, with theNo Comment
user and host
functions. The user
function removes everything starting with the @ to the
end of the address, and host removes everything up to and including
the @. Using the previous example of
nvp@mail.somename.com, the following line:
outputs:print $addr->user;
And the following line using thenvp
host function:
outputs:print $addr->host;
nvp@mail.somename.com
Many networks have machines dedicated to sending and receiving email. Since users might hold accounts on foo.bar.com, while mail is sent to pop-server.bar.com, there must be a means to transfer the mail from the "post office" machine to the host on which the user works. The Post Office Protocol, or POP, negotiates this mail transfer.
When a user wants to retrieve his or her mail, the user's mail client connects to the POP server and authenticates the user with a login name and password, as we described earlier. Once authenticated, the user can list, read, and delete messages from the POP server.
The Mail::POP3Client module simplifies the process of "talking POP" by implementing a number of functions to login, parse, and read mail messages held on the POP server. Information that the POP server needs, such as the user's login name and password, and possibly some optional information (the name of the POP host, the port, and a debugging flag) are passed to the constructor when a new POP3Client object is created. For example:
use Mail::POP3Client;
$pop = Mail::POP3Client->new("login", # required
"password", #required
"pophost.your.domain", # not required
port, # default is 110
debug_flag); # any positive integerThe Count function returns the number of messages
in the mailbox. Once they have been
authenticated, users can list the headers of the messages in their
mailbox using the Head function in conjunction with the Count
function, as shown in the following example:
use strict;
use Mail::POP3Client;
my($pop, $num_mesg, $i);
$pop = Mail::POP3Client->new("nvp",
"xxxxxx");
$num_mesg = $pop->Count; # How many messages are there?
print("You have ".$num_mesg." new message(s).\n");
for ($i = 1; $i <= $num_mesg; $i++) {
print $pop->Head($i), "\n"; #print header for each message
}my($pop, $num_mesg, $i);
$pop = Mail::POP3Client->new("nvp",
"xxxxxx");
for ($i = 1; $i <= $pop->Count; $i++) {
foreach ($pop->Head($i)) {
# output from and subject
print $_." " if /^(From|Subject)/;
}
print "\n";
}The Host method returns or sets the current POP host. For example:
returns the current POP host. To set the new POP host to new-pop.bar.com, you could do this:$obj->Host;
The$new_host = 'new-pop.bar.com'; $obj->Host($new_host);
Port method works like Host, returning or
setting the current port that the POP server is bound to:
$obj->Port; #return the current port for the POP server $new_port = 7000; #set the port to 7000 $obj->Port($new_port);
Naturally, you'll want to read more than the headers of your mail
messages, so you'll want to use the Body, HeadAndBody,
and Retrieve methods. Body outputs the body of the
message, while HeadAndBody and Retrieve are synonyms that
output both the head and the body of the message.
Messages can be deleted from the POP mailbox with the Delete
method. Delete marks messages on the server
for deletion; they aren't permanently removed until a QUIT command is received.
Delete takes one argument - the number of the message to delete:
Like most mail programs, Mail::POP3Client can undelete messages that have been marked for deletion. Use the$pop->Delete(1); #delete the first message
Reset method to do this:
$pop->Reset(1); #undelete the first message
Most programs that require a user to log in will time out after a certain
period of time for security and resource reasons. The Alive
method checks to see if the connection to the POP server is still open; it
returns true if the connection is good, and false otherwise.
POP connections can be explicitly opened and closed with Login and
Close. Close takes no arguments and closes
the connection to the POP server.
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