
=head1 NAME

Mail::Box::POP3 - handle POP3 folders as client


=head1 INHERITANCE

 Mail::Box::POP3
   is a Mail::Box::Net
   is a Mail::Box
   is a Mail::Reporter


=head1 SYNOPSIS

 use Mail::Box::POP3;
 my $folder = new Mail::Box::POP3 folder => $ENV{MAIL}, ...;


=head1 DESCRIPTION

Maintain a folder which has its messages stored on a remote server.  The
communication between the client application and the server is implemented
using the POP3 protocol.  This class uses L<Mail::Transport::POP3|Mail::Transport::POP3> to
hide the transport of information, and focusses solely on the correct
handling of messages within a POP3 folder.


=head1 OVERLOADED


overload: B<"">

=over 4

See L<Mail::Box/"OVERLOADED">

=back

overload: B<@{}>

=over 4

See L<Mail::Box/"OVERLOADED">

=back

overload: B<cmp>

=over 4

See L<Mail::Box/"OVERLOADED">

=back


=head1 METHODS


=head2 Constructors


$obj-E<gt>B<create>(FOLDER, OPTIONS)

Mail::Box::POP3-E<gt>B<create>(FOLDER, OPTIONS)

=over 4

It is not possible to create a new folder on a POP3 server.  This method
will always return C<false>.

 Option     Defined in    Default   
 folderdir  L<Mail::Box>  <not used>

. folderdir DIRECTORY

=back

Mail::Box::POP3-E<gt>B<new>(OPTIONS)

=over 4

For authentications, you have three choices: specify a foldername which
resembles an URL, or specify a pop-client object, or separate options
for user, password, pop-server and server-port.

 Option             Defined in       Default                                                         
 access             L<Mail::Box>     C<'r'>                                                          
 authenticate                        C<'AUTO'>                                                       
 body_delayed_type  L<Mail::Box>     L<Mail::Message::Body::Delayed|Mail::Message::Body::Delayed>    
 body_type          L<Mail::Box>     L<Mail::Message::Body::Lines|Mail::Message::Body::Lines>        
 coerce_options     L<Mail::Box>     C<[]>                                                           
 create             L<Mail::Box>     <not applicable>                                                
 extract            L<Mail::Box>     C<10240>                                                        
 field_type         L<Mail::Box>     undef                                                           
 fix_headers        L<Mail::Box>     <false>                                                         
 folder             L<Mail::Box>     C<'/'>                                                          
 folderdir          L<Mail::Box>     <not used>                                                      
 head_delayed_type  L<Mail::Box>     L<Mail::Message::Head::Delayed|Mail::Message::Head::Delayed>    
 head_type          L<Mail::Box>     L<Mail::Message::Head::Complete|Mail::Message::Head::Complete>  
 keep_dups          L<Mail::Box>     <false>                                                         
 lock_file          L<Mail::Box>     undef                                                           
 lock_timeout       L<Mail::Box>     1 hour                                                          
 lock_type          L<Mail::Box>     C<'NONE'>                                                       
 lock_wait          L<Mail::Box>     10 seconds                                                      
 locker             L<Mail::Box>     undef                                                           
 log                L<Mail::Reporter>  C<'WARNINGS'>                                                   
 manager            L<Mail::Box>     undef                                                           
 message_type       L<Mail::Box>     L<Mail::Box::POP3::Message|Mail::Box::POP3::Message>            
 multipart_type     L<Mail::Box>     L<Mail::Message::Body::Multipart|Mail::Message::Body::Multipart>
 password           L<Mail::Box::Net>  undef                                                           
 pop_client                          undef                                                           
 remove_when_empty  L<Mail::Box>     <false>                                                         
 save_on_exit       L<Mail::Box>     <true>                                                          
 server_name        L<Mail::Box::Net>  undef                                                           
 server_port        L<Mail::Box::Net>  110                                                             
 trace              L<Mail::Reporter>  C<'WARNINGS'>                                                   
 trusted            L<Mail::Box>     <false>                                                         
 username           L<Mail::Box::Net>  undef                                                           

. access MODE

. authenticate 'LOGIN'|'APOP'|'AUTO'

=over 4

POP3 can use two methods of authentication: the old LOGIN protocol, which
transmits a username and password in plain text, and the newer APOP
protocol which uses MD5 encryption.  APOP is therefore much better, however
not always supported by the server.  With AUTO, first APOP is tried and
if that fails LOGIN.

=back

. body_delayed_type CLASS

. body_type CLASS|CODE

. coerce_options ARRAY

. create BOOLEAN

. extract INTEGER | CODE | METHOD | 'LAZY'|'ALWAYS'

. field_type CLASS

. fix_headers BOOLEAN

. folder FOLDERNAME

. folderdir DIRECTORY

. head_delayed_type CLASS

. head_type CLASS

. keep_dups BOOLEAN

. lock_file FILENAME

. lock_timeout SECONDS

. lock_type CLASS|STRING|ARRAY

. lock_wait SECONDS

. locker OBJECT

. log LEVEL

. manager MANAGER

. message_type CLASS

. multipart_type CLASS

. password STRING

. pop_client OBJECT

=over 4

You may want to specify your own pop-client object.  The object
which is passed must extend L<Mail::Transport::POP3|Mail::Transport::POP3>.

=back

. remove_when_empty BOOLEAN

. save_on_exit BOOLEAN

. server_name HOSTNAME

. server_port INTEGER

. trace LEVEL

. trusted BOOLEAN

. username STRING

I<Example:> 

 my $url = 'pop3://user:password@pop.xs4all.nl'
 my $pop = Mail::Box::POP3->new($url);

 my $pop = $mgr->open(type => 'pop3',
    username => 'myname', password => 'mypassword',
    server_name => 'pop.xs4all.nl');

=back

=head2 The folder


$obj-E<gt>B<addMessage>(MESSAGE)

=over 4

It is impossible to write messages to the average POP3 server.  There are
extensions to the protocol which do permit it, however these are not
implemented (yet, patches welcome).

C<undef> is returned, and an error displayed.  However, no complaint is
given when the MESSAGE is C<undef> itself.

=back

$obj-E<gt>B<addMessages>(MESSAGES)

=over 4

As useless as L<addMessage()|Mail::Box::POP3/"METHODS">.  The only acceptable call to this method
is without any message.

=back

Mail::Box::POP3-E<gt>B<appendMessages>(OPTIONS)

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<close>(OPTIONS)

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<copyTo>(FOLDER, OPTIONS)

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<delete>

=over 4

It is not possible to delete a POP3 folder remotely: the best we can do
is remove all the messages in it... which is the action implemented here.
A notice is logged about this.

=back

$obj-E<gt>B<folderdir>([DIRECTORY])

=over 4

See L<Mail::Box::Net/"METHODS">

=back

Mail::Box::POP3-E<gt>B<foundIn>([FOLDERNAME], OPTIONS)

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<name>

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<organization>

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<size>

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<type>

=over 4

See L<Mail::Box/"The folder">

=back

$obj-E<gt>B<update>

=over 4

NOT IMPLEMENTED YET

=back

$obj-E<gt>B<url>

=over 4

See L<Mail::Box/"The folder">

=back

=head2 Folder flags


$obj-E<gt>B<isModified>

=over 4

See L<Mail::Box/"Folder flags">

=back

$obj-E<gt>B<modified>([BOOLEAN])

=over 4

See L<Mail::Box/"Folder flags">

=back

$obj-E<gt>B<writable>

=over 4

See L<Mail::Box/"Folder flags">

=back

=head2 The messages


$obj-E<gt>B<current>([NUMBER|MESSAGE|MESSAGE-ID])

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<find>(MESSAGE-ID)

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<findFirstLabeled>(LABEL, [BOOLEAN, [ARRAY-OF-MSGS]])

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<message>(INDEX [,MESSAGE])

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<messageId>(MESSAGE-ID [,MESSAGE])

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<messageIds>

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<messages>(['ALL',RANGE,'ACTIVE','DELETED',LABEL,!LABEL,FILTER])

=over 4

See L<Mail::Box/"The messages">

=back

$obj-E<gt>B<scanForMessages>(MESSAGE, MESSAGE-IDS, TIMESPAN, WINDOW)

=over 4

See L<Mail::Box/"The messages">

=back

=head2 Sub-folders


$obj-E<gt>B<listSubFolders>(OPTIONS)

Mail::Box::POP3-E<gt>B<listSubFolders>(OPTIONS)

=over 4

The standard POP3 protocol does not support sub-folders, so an
empty list will be returned in any case.

 Option      Defined in       Default      
 check       L<Mail::Box>     <false>      
 folder      L<Mail::Box>     <required>   
 folderdir   L<Mail::Box>     <from folder>
 skip_empty  L<Mail::Box>     <false>      

. check BOOLEAN

. folder FOLDERNAME

. folderdir DIRECTORY

. skip_empty BOOL

=back

$obj-E<gt>B<nameOfSubFolder>(NAME)

=over 4

See L<Mail::Box/"Sub-folders">

=back

$obj-E<gt>B<openRelatedFolder>(OPTIONS)

=over 4

See L<Mail::Box/"Sub-folders">

=back

$obj-E<gt>B<openSubFolder>(OPTIONS)

=over 4

It is not possible to open a sub-folder for a POP3 folder, because that
is not supported by the official POP3 protocol. In any case, C<undef>
is returned to indicate a failure.

=back

=head2 Internals


$obj-E<gt>B<coerce>(MESSAGE)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<determineBodyType>(MESSAGE, HEAD)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<getHead>(MESSAGE)

=over 4

Read the header for the specified message from the remote server.

=back

$obj-E<gt>B<getHeadAndBody>(MESSAGE)

=over 4

Read all data for the specified message from the remote server.

=back

$obj-E<gt>B<lineSeparator>([STRING|'CR'|'LF'|'CRLF'])

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<locker>

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<popClient>

=over 4

Returns the pop client object.  This does not establish the connection.

=back

$obj-E<gt>B<read>(OPTIONS)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<readMessages>(OPTIONS)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<storeMessage>(MESSAGE)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<toBeThreaded>(MESSAGES)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<toBeUnthreaded>(MESSAGES)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<updateMessages>(OPTIONS)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<write>(OPTIONS)

=over 4

See L<Mail::Box/"Internals">

=back

$obj-E<gt>B<writeMessages>(OPTIONS)

=over 4

 Option    Defined in    Default   
 messages  L<Mail::Box>  <required>

. messages ARRAY

=back

=head2 Other methods


$obj-E<gt>B<timespan2seconds>(TIME)

Mail::Box::POP3-E<gt>B<timespan2seconds>(TIME)

=over 4

See L<Mail::Box/"Other methods">

=back

=head2 Error handling


$obj-E<gt>B<AUTOLOAD>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<addReport>(OBJECT)

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<defaultTrace>([LEVEL, [LEVEL])

Mail::Box::POP3-E<gt>B<defaultTrace>([LEVEL, [LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<errors>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<log>([LEVEL [,STRINGS]])

Mail::Box::POP3-E<gt>B<log>([LEVEL [,STRINGS]])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<logPriority>(LEVEL)

Mail::Box::POP3-E<gt>B<logPriority>(LEVEL)

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<logSettings>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<notImplemented>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<report>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<reportAll>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<trace>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<warnings>

=over 4

See L<Mail::Reporter/"Error handling">

=back

=head2 Cleanup


$obj-E<gt>B<DESTROY>

=over 4

See L<Mail::Box/"Cleanup">

=back

$obj-E<gt>B<inGlobalDestruction>

=over 4

See L<Mail::Reporter/"Cleanup">

=back



=head1 DIAGNOSTICS

I<Notice:> A POP3 folder cannot be deleted: it will be emptied.

Each user has only one POP3 folder on a server.  This folder is created and
deleted by the server's administrator only.  A delete can only remove the
messages in the folder for you.

I<Error:> Cannot create POP3 client for $name.

The connection to the POP3 server cannot be established.  You may see
more, related, error messages about the failure.

I<Error:> Cannot find head back for $uidl on POP3 server $name.

The server told to have this message, but when asked for its headers, no
single line was returned.  Did the message get destroyed?

I<Error:> Cannot read body for $uidl on POP3 server $name.

The message's headers are retreived from the server, but the body seems
to be lost.  Did the message get destroyed between reading the header
and reading the body?

I<Warning:> Changes not written to read-only folder $self.

You have opened the folder read-only --which is the default set
by L<new(access)|Mail::Box/"Constructors">--, made modifications, and now want to close it.
Set L<close(force)|Mail::Box/"The folder"> if you want to overrule the access mode, or close
the folder with L<close(write)|Mail::Box/"The folder"> set to C<NEVER>.

I<Error:> Copying failed for one message.

For some reason, for instance disc full, removed by external process, or
read-protection, it is impossible to copy one of the messages.  Copying will
proceed for the other messages.

I<Error:> Destination folder $name is not writable.

The folder where the messages are copied to is not opened with write
access (see L<new(access)|Mail::Box/"Constructors">).  This has no relation with write permission
to the folder which is controled by your operating system.

I<Warning:> Different messages with id $msgid.

The message id is discovered more than once within the same folder, but the
content of the message seems to be different.  This should not be possible:
each message must be unique.

I<Error:> Folder $name is opened read-only

You can not write to this folder unless you have opened the folder to
write or append with L<new(access)|Mail::Box/"Constructors">, or the C<force> option is set true.

I<Error:> Invalid timespan '$timespan' specified.

The string does not follow the strict rules of the time span syntax which
is permitted as parameter.

I<Warning:> Message $uidl on POP3 server $name disappeared.

The server indicated the existence of this message before, however it
has no information about the message anymore.

I<Warning:> Message-id '$msgid' does not contain a domain.

According to the RFCs, message-ids need to contain a unique random part,
then an C<@>, and then a domain name.  This is made to avoid the creation
of two messages with the same id.  The warning emerges when the C<@> is
missing from the string.

I<Error:> Package $package does not implement $method.

Fatal error: the specific package (or one of its superclasses) does not
implement this method where it should. This message means that some other
related classes do implement this method however the class at hand does
not.  Probably you should investigate this and probably inform the author
of the package.

I<Error:> Unable to create subfolder $name of $folder.

The copy includes the subfolders, but for some reason it was not possible
to copy one of these.  Copying will proceed for all other sub-folders.

I<Error:> Update of $nr messages ignored for POP3 folder $name.

The standard POP3 implementation does not support writing from client back
to the server.  Therefore, modifications may be lost.

I<Error:> Writing folder $name failed

For some reason (you probably got more error messages about this problem)
it is impossible to write the folder, although you should because there
were changes made.

I<Error:> You cannot write a message to a pop server (yet)

Some extensions to the POP3 protocol do permit writing messages to the server,
but the standard protocol only implements retreival.  Feel invited to extend our
implementation with writing.


=head1 DETAILS


=head2 How POP3 folders work

Rfc1939 defines how POP3 works.  POP3 is a really simple protocol to
receive messages from a server to a user's client.  POP3 is also
really limited: it can only be used to fetch messages, but has not
many ways to limit the amount of network traffic, like the IMAP4
protocol has.

One POP3 account represents only one folder: there is no way of
sub-folders in POP3.  POP3 doesn't support writing (except for
some message status flags).

=head2 This implementation

The protocol specifics are implemented in L<Mail::Transport::POP3|Mail::Transport::POP3>,
written by Liz Mattijsen.  That module does not use any of the
other POP3 modules available on CPAN for the reason that MailBox
tries to be smarter: it is capable of re-establishing broken POP3
connection when the server supports UIDs.

The implementation has shown to work with many different POP servers.
In the test directory of the distribution, you will find a small
server implementation, which is used to test the client.





=head1 REFERENCES

See the MailBox website at L<http://perl.overmeer.net/mailbox/> for more details.

=head1 COPYRIGHTS

Distribution version 2.056.
Written by Mark Overmeer (mark@overmeer.net).  See the ChangeLog for
other contributors.

Copyright (c) 2001-2003 by the author(s). All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.


