Mail::Box::MH - handle MH folders

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

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

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

overload: "" See OVERLOADED in Mail::Box

overload: @{} See OVERLOADED in Mail::Box

overload: cmp See OVERLOADED in Mail::Box

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>

$obj->addMessage(MESSAGE, OPTIONS) See The folder in Mail::Box

$obj->addMessages(MESSAGE [, MESSAGE, ...]) See The folder in Mail::Box

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>

$obj->close(OPTIONS) See The folder in Mail::Box

$obj->copyTo(FOLDER, OPTIONS) See The folder in Mail::Box

$obj->delete(OPTIONS) See The folder in Mail::Box

$obj->directory See The folder in Mail::Box::Dir

$obj->folderdir([DIRECTORY]) See The folder in Mail::Box

$obj->name See The folder in Mail::Box

$obj->organization See The folder in Mail::Box

$obj->size See The folder in Mail::Box

$obj->type See The folder in Mail::Box

$obj->update(OPTIONS) See The folder in Mail::Box

$obj->url See The folder in Mail::Box

$obj->access See Folder flags in Mail::Box

$obj->isModified See Folder flags in Mail::Box

$obj->modified([BOOLEAN]) See Folder flags in Mail::Box

$obj->writable See Folder flags in Mail::Box

$obj->current([NUMBER|MESSAGE|MESSAGE-ID]) See The messages in Mail::Box

$obj->find(MESSAGE-ID) See The messages in Mail::Box

$obj->findFirstLabeled(LABEL, [BOOLEAN, [ARRAY-OF-MSGS]]) See The messages in Mail::Box

$obj->message(INDEX [,MESSAGE]) See The messages in Mail::Box

$obj->messageId(MESSAGE-ID [,MESSAGE]) See The messages in Mail::Box

$obj->messageIds See The messages in Mail::Box

$obj->messages(['ALL',RANGE,'ACTIVE','DELETED',LABEL,!LABEL,FILTER]) See The messages in Mail::Box

$obj->nrMessages(OPTIONS) See The messages in Mail::Box

$obj->scanForMessages(MESSAGE, MESSAGE-IDS, TIMESPAN, WINDOW) See The messages in Mail::Box

$obj->listSubFolders(OPTIONS)

Mail::Box::MH->listSubFolders(OPTIONS) See Sub-folders in Mail::Box

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

Mail::Box::MH->nameOfSubFolder(SUBNAME, [PARENTNAME]) See Sub-folders in Mail::Box

$obj->openRelatedFolder(OPTIONS) See Sub-folders in Mail::Box

$obj->openSubFolder(SUBNAME, OPTIONS) See Sub-folders in Mail::Box

$obj->topFolderWithMessages

Mail::Box::MH->topFolderWithMessages See Sub-folders in Mail::Box

$obj->coerce(MESSAGE, OPTIONS) See Internals in Mail::Box

$obj->create(FOLDERNAME, OPTIONS)

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

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

$obj->determineBodyType(MESSAGE, HEAD) See Internals in Mail::Box

$obj->folderToDirectory(FOLDERNAME, FOLDERDIR) See Internals in Mail::Box::Dir

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

$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 Mail::Box

$obj->locker See Internals in Mail::Box

$obj->read(OPTIONS) See Internals in Mail::Box

$obj->readMessageFilenames(DIRECTORY) See Internals in Mail::Box::Dir

$obj->readMessages(OPTIONS) See Internals in Mail::Box

$obj->storeMessage(MESSAGE) See Internals in Mail::Box

$obj->toBeThreaded(MESSAGES) See Internals in Mail::Box

$obj->toBeUnthreaded(MESSAGES) See Internals in Mail::Box

$obj->updateMessages(OPTIONS) See Internals in Mail::Box

$obj->write(OPTIONS) See Internals in Mail::Box

$obj->writeMessages(OPTIONS)

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

$obj->timespan2seconds(TIME)

Mail::Box::MH->timespan2seconds(TIME) See Other methods in Mail::Box

$obj->AUTOLOAD See Error handling in Mail::Reporter

$obj->addReport(OBJECT) See Error handling in Mail::Reporter

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

Mail::Box::MH->defaultTrace([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK]) See Error handling in Mail::Reporter

$obj->errors See Error handling in Mail::Reporter

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

Mail::Box::MH->log([LEVEL [,STRINGS]]) See Error handling in Mail::Reporter

$obj->logPriority(LEVEL)

Mail::Box::MH->logPriority(LEVEL) See Error handling in Mail::Reporter

$obj->logSettings See Error handling in Mail::Reporter

$obj->notImplemented See Error handling in Mail::Reporter

$obj->report([LEVEL]) See Error handling in Mail::Reporter

$obj->reportAll([LEVEL]) See Error handling in Mail::Reporter

$obj->trace([LEVEL]) See Error handling in Mail::Reporter

$obj->warnings See Error handling in Mail::Reporter

$obj->DESTROY See Cleanup in Mail::Box

$obj->inGlobalDestruction See Cleanup in Mail::Reporter

Error: Cannot append message without lock on CW$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 CW$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 CW$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 CW$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 CWNEVER.

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 CW$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 CW$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 CW$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 CWforce option is set true.

Error: Folder CW$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 CWdelete 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 CW@, and then a domain name. This is made to avoid the creation of two messages with the same id. The warning emerges when the CW@ is missing from the string.

Error: Package CW$package does not implement CW$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 CW$name of CW$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 CW$folder to CW$filename: $!

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

Error: Writing folder CW$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.

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 CW1. Next to these message files, a directory may contain a file named CW.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 supports the CW.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.

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 CW.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.

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

Distribution version 2.063. 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.