Mail::Box::MH - handle MH folders

NAME

Mail::Box::MH - handle MH folders

INHERITANCE

 Mail::Box::MH
   is a Mail::Box::Dir
   is a Mail::Box
   is a Mail::Reporter

SYNOPSIS

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

DESCRIPTION

This documentation describes how MH mailboxes work, and what you can do with the MH folder object Mail::Box::MH.

OVERLOADED

overload: ``''

See OVERLOADED in the Mail::Box manpage

overload: @{}

See OVERLOADED in the Mail::Box manpage

overload: cmp

See OVERLOADED in the Mail::Box manpage

METHODS

Constructors

Mail::Box::MH->new(OPTIONS)

 Option             Defined in       Default                                                         
 access             L<Mail::Box>     C<'r'>                                                          
 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>     <false>                                                         
 directory          L<Mail::Box::Dir>  <derived from folder name>                                      
 extract            L<Mail::Box>     C<10240>                                                        
 field_type         L<Mail::Box>     undef                                                           
 fix_headers        L<Mail::Box>     <false>                                                         
 folder             L<Mail::Box>     C<$ENV{MAIL}>                                                   
 folderdir          L<Mail::Box>     C<$ENV{HOME}/.mh>                                               
 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>  
 index                               undef                                                           
 index_filename                      <foldername>C</.index>                                          
 index_type                          L<Mail::Box::MH::Index|Mail::Box::MH::Index>                    
 keep_dups          L<Mail::Box>     <false>                                                         
 keep_index                          0                                                               
 labels                              undef                                                           
 labels_filename                     <foldername>C</.mh_sequence>                                    
 labels_type                         L<Mail::Box::MH::Labels|Mail::Box::MH::Labels>                  
 lock_file          L<Mail::Box>     <index_file>                                                    
 lock_timeout       L<Mail::Box>     1 hour                                                          
 lock_type          L<Mail::Box>     L<Mail::Box::Locker::DotLock|Mail::Box::Locker::DotLock>        
 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::Message|Mail::Box::Message>                        
 multipart_type     L<Mail::Box>     L<Mail::Message::Body::Multipart|Mail::Message::Body::Multipart>
 remove_when_empty  L<Mail::Box>     <true>                                                          
 save_on_exit       L<Mail::Box>     <true>                                                          
 trace              L<Mail::Reporter>  C<'WARNINGS'>                                                   
 trusted            L<Mail::Box>     <depends on folder location>

. access MODE

. body_delayed_type CLASS

. body_type CLASS|CODE

. coerce_options ARRAY

. create BOOLEAN

. directory DIRECTORY

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

. field_type CLASS

. fix_headers BOOLEAN

. folder FOLDERNAME

. folderdir DIRECTORY

. head_delayed_type CLASS

. head_type CLASS

. index OBJECT

You may specify an OBJECT of a type which extends Mail::Box::MH::Index (at least implements a get() method), as alternative for an index file reader as created by Mail::Box::MH.

. index_filename FILENAME

The FILENAME which is used in each directory to store the headers of all mails. The filename shall not contain a directory path. (e.g. Do not use /usr/people/jan/.index, nor subdir/.index, but say .index.)

. index_type CLASS

. keep_dups BOOLEAN

. keep_index BOOLEAN

Keep an index file of the specified mailbox, one file per directory. Using an index file will speed up things considerably, because it avoids reading all the message files the moment that you open the folder. When you open a folder, you can use the index file to retrieve information such as the subject of each message, instead of having to read possibly thousands of messages.

. labels OBJECT

You may specify an OBJECT of a type which extends Mail::Box::MH::Labels (at least implements the get() method), as alternative for labels file reader as created by Mail::Box::MH.

. labels_filename FILENAME

In MH-folders, messages can be labeled, for instance based on the sender or whether it is read or not. This status is kept in a file which is usually called .mh_sequences, but that name can be overruled with this flag.

. labels_type CLASS

. 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

. remove_when_empty BOOLEAN

. save_on_exit BOOLEAN

. trace LEVEL

. trusted BOOLEAN

The folder

$obj->addMessage(MESSAGE, OPTIONS)

See The folder in the Mail::Box manpage

$obj->addMessages(MESSAGE [, MESSAGE, ...])

See The folder in the Mail::Box manpage

Mail::Box::MH->appendMessages(OPTIONS)

Append a message to a folder which is not open.

 Option    Defined in       Default   
 folder    L<Mail::Box>     <required>
 message   L<Mail::Box>     undef     
 messages  L<Mail::Box>     undef     
 share     L<Mail::Box>     <false>

. folder FOLDERNAME

. message MESSAGE

. messages ARRAY-OF-MESSAGES

. share BOOLEAN

$obj->close(OPTIONS)

See The folder in the Mail::Box manpage

$obj->copyTo(FOLDER, OPTIONS)

See The folder in the Mail::Box manpage

$obj->delete(OPTIONS)

See The folder in the Mail::Box manpage

$obj->directory

See The folder in the Mail::Box::Dir manpage

$obj->folderdir([DIRECTORY])

See The folder in the Mail::Box manpage

$obj->name

See The folder in the Mail::Box manpage

$obj->organization

See The folder in the Mail::Box manpage

$obj->size

See The folder in the Mail::Box manpage

$obj->type

See The folder in the Mail::Box manpage

$obj->update(OPTIONS)

See The folder in the Mail::Box manpage

$obj->url

See The folder in the Mail::Box manpage

Folder flags

$obj->access

See Folder flags in the Mail::Box manpage

$obj->isModified

See Folder flags in the Mail::Box manpage

$obj->modified([BOOLEAN])

See Folder flags in the Mail::Box manpage

$obj->writable

See Folder flags in the Mail::Box manpage

The messages

$obj->current([NUMBER|MESSAGE|MESSAGE-ID])

See The messages in the Mail::Box manpage

$obj->find(MESSAGE-ID)

See The messages in the Mail::Box manpage

$obj->findFirstLabeled(LABEL, [BOOLEAN, [ARRAY-OF-MSGS]])

See The messages in the Mail::Box manpage

$obj->message(INDEX [,MESSAGE])

See The messages in the Mail::Box manpage

$obj->messageId(MESSAGE-ID [,MESSAGE])

See The messages in the Mail::Box manpage

$obj->messageIds

See The messages in the Mail::Box manpage

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

See The messages in the Mail::Box manpage

$obj->nrMessages(OPTIONS)

See The messages in the Mail::Box manpage

$obj->scanForMessages(MESSAGE, MESSAGE-IDS, TIMESPAN, WINDOW)

See The messages in the Mail::Box manpage

Sub-folders

$obj->listSubFolders(OPTIONS)

Mail::Box::MH->listSubFolders(OPTIONS)

See Sub-folders in the Mail::Box manpage

$obj->nameOfSubFolder(SUBNAME, [PARENTNAME])

Mail::Box::MH->nameOfSubFolder(SUBNAME, [PARENTNAME])

See Sub-folders in the Mail::Box manpage

$obj->openRelatedFolder(OPTIONS)

See Sub-folders in the Mail::Box manpage

$obj->openSubFolder(SUBNAME, OPTIONS)

See Sub-folders in the Mail::Box manpage

$obj->topFolderWithMessages

Mail::Box::MH->topFolderWithMessages

See Sub-folders in the Mail::Box manpage

Internals

$obj->coerce(MESSAGE, OPTIONS)

See Internals in the Mail::Box manpage

$obj->create(FOLDERNAME, OPTIONS)

Mail::Box::MH->create(FOLDERNAME, OPTIONS)

 Option     Defined in    Default
 folderdir  L<Mail::Box>  undef

. folderdir DIRECTORY

$obj->determineBodyType(MESSAGE, HEAD)

See Internals in the Mail::Box manpage

$obj->folderToDirectory(FOLDERNAME, FOLDERDIR)

See Internals in the Mail::Box::Dir manpage

Mail::Box::MH->foundIn([FOLDERNAME], OPTIONS)

See Internals in the Mail::Box manpage

$obj->highestMessageNumber

Returns the highest number which is used in the folder to store a file. This method may be called when the folder is read (then this number can be derived without file-system access), but also when the folder is not read (yet).

$obj->index

Create a index reader/writer object.

$obj->labels

Create a label reader/writer object.

$obj->lineSeparator([STRING|'CR'|'LF'|'CRLF'])

See Internals in the Mail::Box manpage

$obj->locker

See Internals in the Mail::Box manpage

$obj->read(OPTIONS)

See Internals in the Mail::Box manpage

$obj->readMessageFilenames(DIRECTORY)

See Internals in the Mail::Box::Dir manpage

$obj->readMessages(OPTIONS)

See Internals in the Mail::Box manpage

$obj->storeMessage(MESSAGE)

See Internals in the Mail::Box manpage

$obj->toBeThreaded(MESSAGES)

See Internals in the Mail::Box manpage

$obj->toBeUnthreaded(MESSAGES)

See Internals in the Mail::Box manpage

$obj->updateMessages(OPTIONS)

See Internals in the Mail::Box manpage

$obj->write(OPTIONS)

See Internals in the Mail::Box manpage

$obj->writeMessages(OPTIONS)

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

. messages ARRAY

. renumber BOOLEAN

Permit renumbering of message. By default this is true, but for some unknown reason, you may be thinking that messages should not be renumbered.

Other methods

$obj->timespan2seconds(TIME)

Mail::Box::MH->timespan2seconds(TIME)

See Other methods in the Mail::Box manpage

Error handling

$obj->AUTOLOAD

See Error handling in the Mail::Reporter manpage

$obj->addReport(OBJECT)

See Error handling in the Mail::Reporter manpage

$obj->defaultTrace([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])

Mail::Box::MH->defaultTrace([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])

See Error handling in the Mail::Reporter manpage

$obj->errors

See Error handling in the Mail::Reporter manpage

$obj->log([LEVEL [,STRINGS]])

Mail::Box::MH->log([LEVEL [,STRINGS]])

See Error handling in the Mail::Reporter manpage

$obj->logPriority(LEVEL)

Mail::Box::MH->logPriority(LEVEL)

See Error handling in the Mail::Reporter manpage

$obj->logSettings

See Error handling in the Mail::Reporter manpage

$obj->notImplemented

See Error handling in the Mail::Reporter manpage

$obj->report([LEVEL])

See Error handling in the Mail::Reporter manpage

$obj->reportAll([LEVEL])

See Error handling in the Mail::Reporter manpage

$obj->trace([LEVEL])

See Error handling in the Mail::Reporter manpage

$obj->warnings

See Error handling in the Mail::Reporter manpage

Cleanup

$obj->DESTROY

See Cleanup in the Mail::Box manpage

$obj->inGlobalDestruction

See Cleanup in the Mail::Reporter manpage

DIAGNOSTICS

Error: Cannot append message without lock on $folder.

It is impossible to append one or more messages to the folder which is not opened, because locking it failes. The folder may be in use by an other application, or you may need to specify some lock related options (see new()).

Error: Cannot create MH folder $name: $!

For some reason, it is impossible to create the folder. Check the permissions and the name of the folder. Does the path to the directory to be created exist?

Error: Cannot write folder $name without lock.

It is impossible to get a lock on the folder, which means that the changes can not be made. You may need to tune the lock related options which are available at folder creation.

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

You have opened the folder read-only --which is the default set by new(access)--, made modifications, and now want to close it. Set close(force) if you want to overrule the access mode, or close the folder with close(write) set to NEVER.

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.

Error: Destination folder $name is not writable.

The folder where the messages are copied to is not opened with write access (see new(access)). This has no relation with write permission to the folder which is controled by your operating system.

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.

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 new(access), or the force option is set true.

Error: Folder $name not deleted: not writable.

The folder must be opened with write access via new(access), otherwise removing it will be refused. So, you may have write-access according to the operating system, but that will not automatically mean that this delete method permits you to. The reverse remark is valid as well.

Error: Invalid timespan '$timespan' specified.

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

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

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

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.

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.

Error: Unable to write message for $folder to $filename: $!

The new message could not be written to its new file, for the specific reason.

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.

DETAILS

How MH folders work

MH-type folders use a directory to store the messages of one folder. Each message is stored in a separate file. This seems useful, because changes in a folder change only a few of these small files, in contrast with file-based folders where changes in a folder cause rewrites of huge folder files.

However, MH-based folders perform very bad if you need header information of all messages. For instance, if you want to have full knowledge about all message-threads (see Mail::Box::Thread::Manager) in the folder, it requires to read all header lines in all message files. And usually, reading your messages in threads is desired.

So, each message is written in a separate file. The filenames are numbers, which count from 1. Next to these message files, a directory may contain a file named .mh_sequences, storing labels which relate to the messages. Furthermore, a folder-directory may contain sub-directories, which are seen as sub-folders.

This implementation

This implementation supports the .mh-sequences file and sub-folders. Next to this, considerable effort it made to avoid reading each message-file. This should boost performance of the MailBox distribution over other Perl-modules which are able to read folders.

Folder types which store their messages each in one file, together in one directory, are bad for performance. Consider that you want to know the subjects of all messages, while browser through a folder with your mail-reading client. This would cause all message-files to be read.

Mail::Box::MH has two ways to try improve performance. You can use an index-file, and use on delay-loading. The combination performs even better. Both are explained in the next sections.

An index-file

If you specify new(keep_index), then all header-lines of all messages from the folder which have been read once, will also be written into one dedicated index-file (one file per folder). The default filename is .index

However, index-files are not supported by any other reader which supports MH (as far as I know). If you read the folders with such I client, it will not cause unrecoverable conflicts with this index-file, but at most be bad for performance.

If you do not (want to) use an index-file, then delay-loading may save your day.

REFERENCES

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

COPYRIGHTS

Distribution version 2.059. 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.

 Mail::Box::MH - handle MH folders