下面就是它的一个实际例子：
Mail host: pop.mailbox.com
Mailbox username: jane
Mailbox password: secret
Mailbox has 77 message(s).当然，仅仅知道消息的数量是远远不够的——你肯定希望知道这些消息的内容。通过Net::POP3的top()方法就能够达到这个目的，它会扫描消息的前X行，并返回一个指向含有已收取数据的数组的参考。下面就是一个例子，（列表B）会取回邮箱里所有消息的前20行：
列表B
#!/bin/perl
# import package
use Net::POP3;
# ask user for critical variables
print "Mail host: ";
$host = <STDIN>;
chomp($host);
print "
";
print "Mailbox username: ";
$user = <STDIN>;
chomp($user);
print "
";
print "Mailbox password: ";
$pass = <STDIN>;
chomp($pass);
# initiate connection
# default timeout = 120 sec
$conn = Net::POP3->new($host) or die("ERROR: Unable to connect.
");
# login
$numMsg = $conn->login($user, $pass) or die("ERROR: Unable to login.
");
# get message numbers
# iterate over list and print first 20 lines of each
if ($numMsg > 0) {
$msgList = $conn->list();
foreach $msg (keys(%$msgList)) {
$ref = $conn->top($msg, 20);
print @$ref;
print "
";
}
} else {
print "Mailbox is empty.
";
}
# close connection
$conn->quit();你可以使用get()方法而不用top()方法，从而收取完整的消息。
如果你希望的话，你可以在命令行通过Getopt::Long模块把服务器的参数传递给程序，下面的列表C显示了这个模块：
列表C
#!/bin/perl
# import packages
use Net::POP3;
use Getopt::Long;
# read command line options
# display usage message in case of error
GetOptions ('h|host=s' => $host,
'u|user=s' => $user,
'p|pass=s' => $pass) or die("Input error. Try calling me with: -h <host> -u <username> -p <password>");
# initiate connection
# default timeout = 120 sec
$conn = Net::POP3->new($host) or die("ERROR: Unable to connect.
");
# login
$numMsg = $conn->login($user, $pass) or die("ERROR: Unable to login.
");
# get message numbers
# iterate over list and print first 20 lines of each
if ($numMsg > 0) {
$msgList = $conn->list();
foreach $msg (keys(%$msgList)) {
$ref = $conn->top($msg, 20);
print @$ref;
print "
";
}
} else {
print "Mailbox is empty.
";
}
# close connection
$conn->quit();这些代码模板会告诉你如何把Net::POP3集成到需要处理电子邮件的应用程序里。自己动手试试吧，祝你编程愉快！
更多内容请看PCdog.com--POP3协议专题
