Mail::Box::Mbox - handle folders in Mbox format


   is a Mail::Box::File
   is a Mail::Box
   is a Mail::Reporter


 use Mail::Box::Mbox;
 my $folder = Mail::Box::Mbox->new(folder => $ENV{MAIL}, ...);


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


overload: ""

overload: @{}

overload: cmp




     Option             --Defined in     --Default
     access               Mail::Box        'r'
     body_delayed_type    Mail::Box        Mail::Message::Body::Delayed
     body_type            Mail::Box::File  <see description>
     coerce_options       Mail::Box        []
     create               Mail::Box        <false>
     extract              Mail::Box        10240
     field_type           Mail::Box        undef
     fix_headers          Mail::Box        <false>
     folder               Mail::Box        $ENV{MAIL}
     folderdir            Mail::Box        $ENV{HOME}.'/Mail'
     head_delayed_type    Mail::Box        Mail::Message::Head::Delayed
     head_type            Mail::Box        Mail::Message::Head::Complete
     keep_dups            Mail::Box        <false>
     lock_extension       Mail::Box::File  '.lock'
     lock_file            Mail::Box        <foldername><lock-extension>
     lock_timeout         Mail::Box        1 hour
     lock_type            Mail::Box        Mail::Box::Locker::DotLock
     lock_wait            Mail::Box        10 seconds
     locker               Mail::Box        undef
     log                  Mail::Reporter   'WARNINGS'
     manager              Mail::Box        undef
     message_type         Mail::Box        Mail::Box::Mbox::Message
     multipart_type       Mail::Box        Mail::Message::Body::Multipart
     remove_when_empty    Mail::Box        <true>
     save_on_exit         Mail::Box        <true>
     subfolder_extension                   '.d'
     trace                Mail::Reporter   'WARNINGS'
     trusted              Mail::Box        <depends on folder location>
     write_policy         Mail::Box::File  undef

    . access => MODE

    . 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_extension => FILENAME|STRING

    . 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

    . subfolder_extension => STRING

      Mbox folders do not support sub-folders. However, this module can simulate sub-directories if the user wants it to. When a subfolder of folder xyz is created, we create a directory which is called xyz.d to contain them. This extension .d can be changed using this option.

    . trace => LEVEL

    . trusted => BOOLEAN

    . write_policy => 'REPLACE'|'INPLACE'|undef

The folder

$obj->addMessage(MESSAGE, OPTIONS)

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



$obj->copyTo(FOLDER, OPTIONS)










Folder flags





The messages



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

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

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








     Option             --Defined in     --Default
     check                Mail::Box        <false>
     folder               Mail::Box        <from calling object>
     folderdir            Mail::Box        <from folder>
     skip_empty           Mail::Box        <false>
     subfolder_extension                   <from object>

    . check => BOOLEAN

    . folder => FOLDERNAME

    . folderdir => DIRECTORY

    . skip_empty => BOOL

    . subfolder_extension => STRING

      When the method is called on an open folder, the extension defined by it is used to detect sub-folders by default. Otherwise, '.d' is taken.

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

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


$obj->openSubFolder(SUBNAME, OPTIONS)




$obj->coerce(MESSAGE, OPTIONS)


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

     Option             --Defined in     --Default
     folderdir            Mail::Box        undef
     subfolder_extension                   undef

    . folderdir => DIRECTORY

    . subfolder_extension => STRING

      If a directory is found on the location of the folder to be created, this STRING is used to extend that directory name with. This will cause the directory to be seen as sub-folder for the created folder. This argument is passed to folderToFilename().

$obj->determineBodyType(MESSAGE, HEAD)


Mail::Box::Mbox->folderToFilename(FOLDERNAME, FOLDERDIR, [EXTENSION])

    Translate a folder name into a filename, using the FOLDERDIR value to replace a leading =. If no EXTENSION is specified and this method is called as instance method, new(subfolder_extension) is used. Otherwise, the extension default to '.d'.

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

    If no FOLDERNAME is specified, then the value of the folder option is taken. A mbox folder is a file which starts with a separator line: a line with 'From ' as first characters. Blank lines which start the file are ignored, which is not for all MUA's acceptable.

     Option             --Defined in     --Default
     folder                                undef
     folderdir            Mail::Box        undef
     subfolder_extension                   <from object>

    . folder => FOLDERNAME

    . folderdir => DIRECTORY

    . subfolder_extension => STRING



$obj->messageCreateOptions([TYPE, CONFIG])

$obj->moveAwaySubFolder(DIRECTORY, EXTENSION)










File based folders

Other methods



Error handling






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

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













How MBOX folders work

MBOX folders store many messages in one file. Each message begins with a line which starts with the string From . Lines inside a message which accidentally start with From are, in the file, preceded by `>'. This character is stripped when the message is read.

In this respect must be noted that the format of the MBOX files is not strictly defined. The exact content of the separator lines differ between Mail User Agents (MUA's). Besides, some MUAs (like mutt) forget to encode the From lines within message bodies, breaking other parsers....

Simulation of sub-folders

MBOX folders do not have a sub-folder concept as directory based folders do, but this MBOX module tries to simulate them. In this implementation a directory like


is taken as an empty folder Mail/subject1, with the folders in that directory as sub-folders for it. You may also use


where Mail/subject1 is the folder, and the folders in the Mail/subject1.d directory are used as sub-folders. If your situation is similar to the first example and you want to put messages in that empty folder, the directory is automatically (and transparently) renamed, so that the second situation is reached.


Error: Cannot append messages to folder file $filename: $!

    Appending messages to a not-opened file-organized folder may fail when the operating system does not allow write access to the file at hand.

Error: Cannot move away sub-folder $dir

Warning: Cannot remove folder $name file $filename: $!

    Writing an empty folder will usually cause that folder to be removed, which fails for the indicated reason. new(remove_when_empty)

Warning: Cannot remove folder $name file $filename: $!

    Writing an empty folder will usually cause that folder to be removed, which fails for the indicated reason. new(remove_when_empty) controls whether the empty folder will removed; setting it to false (0) may be needed to avoid this message.

Error: Cannot replace $filename by $tempname, to update folder $name: $!

    The replace policy wrote a new folder file to update the existing, but was unable to give the final touch: replacing the old version of the folder file for the indicated reason.

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: File too short to get write message $nr ($size, $need)

    Mail::Box is lazy: it tries to leave messages in the folders until they are used, which saves time and memory usage. When this message appears, something is terribly wrong: some lazy message are needed for updating the folder, but they cannot be retreived from the original file anymore. In this case, messages can be lost.

    This message does appear regularly on Windows systems when using the 'replace' write policy. Please help to find the cause, probably something to do with Windows incorrectly handling multiple filehandles open in the same file.

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 update folder $self.

    When a folder is to be written, both replace and inplace write policies are tried, If both fail, the whole update fails. You may see other, related, error messages to indicate the real problem.


This module is part of Mail-Box distribution version 2.084, built on September 26, 2008. Website:


Copyrights 2001-2008 by Mark Overmeer. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See