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Release Notes

This section highlights important changes that have occurred and important
usage details which you should be aware of before using MHonArc. If you are
upgrading from a previous release, make sure to check for the highlighted
incompatibilites from earlier releases.

NOTE: Read the CHANGES document included in the distribution for a more
      complete summary of changes to MHonArc.

  • Compatibility Notes
      □ UPGRADING FROM v2.6.11 OR EARLIER: Handling of return value for
        $mhonarc::CB{Raw}MessageBodyRead Changed
      □ UPGRADING FROM v2.5.x OR EARLIER: Default iso-2022-jp Converter
        Changed
      □ UPGRADING FROM v2.4.x OR EARLIER: DEFRCNAME Change
      □ UPGRADING FROM v2.4.x OR EARLIER: HEADER and FOOTER Removed
      □ UPGRADING FROM v2.4.x OR EARLIER: MIMEFILTERS API Change
      □ UPGRADING FROM v2.1.x OR EARLIER: Database Format Change
      □ DOWNGRADING TO OLDER VERSIONS
  • v2.6.9 Notes
      □ Attachment filename format change
      □ mhonarc::write_attachment: API change
  • v2.6.0 Notes
      □ m2h_text_html::filter: default argument removed
      □ SPAMMODE: Applies to message body text.
      □ readmail::MAILhead_get_disposition: API change.
  • General Notes
      □ Japanese and MHonArc
      □ Auto-loaded URL attributes stripped in HTML messages
      □ iso8859.pl deprecated
      □ TSLICE range setting
      □ MHonArc code under the mhonarc namespace
      □ HTMLEXT and MSGPREFIX usage warning
      □ Applying new MIMEFILTERS settings

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Compatibility Notes

This sections provides notes dealing with compatibility issues if upgrading
from a previous release of MHonArc:

UPGRADING FROM v2.6.11 OR EARLIER: Handling of return value for
$mhonarc::CB{Raw}MessageBodyRead Changed

NOTE: If you do not utilize MHonArc's callback API, you can ignore this
      compatibility item. However, if you use the mha-preview example
      script, continuing reading.

In v2.6.12, the return value for the $mhonarc::CBMessageBodyRead and
$mhonarc::CBRawMessageBodyRead is now checked to see if the message should
be excluded from further processing. In previous versions, the return value
was N/A. Therefore, if you use either of these callbacks, and the return
value of your routines evaluates to false for a given message, the message
will be excluded from the archive.

If you never want to exclude messages with either of these callbacks, have
your routines always return 1.

NOTE: The example mha-preview script provided in the MHonArc distribution
      has been updated to reflect the change in return value handling. Even
      though it is statistically unlikely messages will be quietly excluded
      with older versions of the script; it is recommended to replace your
      copy with the latest version.

UPGRADING FROM v2.5.x OR EARLIER: Default iso-2022-jp Converter Changed

In v2.6, the default charset converter for iso-2022-jp has changed to the
following:

<CharsetConverters>
iso-2022-jp; MHonArc::CharEnt::str2sgml; MHonArc/CharEnt.pm
</CharsetConverters>

This filter converts all Japanese characters into Unicode character entity
references (e.g. &#x7279;) removing the iso-2022-jp encoding. For some
Japanese locales, this type of conversion may not be desired since some
Japanese-aware processing tools may not support Unicode character entity
references. If you want to preserve the iso-2022-jp encoding, you must
explicitly specify the use of iso_2022_jp::str2html via the
CHARSETCONVERTERS resource as follows:

<CharsetConverters>
iso-2022-jp; iso_2022_jp::str2html; iso2022jp.pl
</CharsetConverters>

The change to MHonArc::CharEnt::str2sgml as the default converter for
iso-2022-jp was done to make MHonArc as locale neutral as possible in its
default configuration.

For more information about using MHonArc in a Japanese locale, see
(documents in Japanese): <http://www.mhonarc.jp/>

UPGRADING FROM v2.4.x OR EARLIER: DEFRCNAME Change

The default value for the DEFRCNAME is now called ".mhonarc.mrc", or
"mhonarc.mrc" under Windows and VMS. The old value was ".mhonarc.rc", or
"mhonarc.rc". If you use the default resource file, you will need to rename
the file to match the filenames used for v2.5 and later.

UPGRADING FROM v2.4.x OR EARLIER: HEADER and FOOTER Removed

The HEADER and FOOTER resources are no longer supported. If you are using
these resources, the HEADER content and FOOTER content will be lost once
v2.5, or later, of MHonArc processes an archive containing these resources.

The HEADER and FOOTER resources have been deprecated for a long time since
they only applied to the main index; the thread index has no equivalent.
The IDXPGBEGIN or LISTBEGIN resources can be used to achieve the same
effect of HEADER. The IDXPGEND or LISTEND can be used to achieve the same
effect of FOOTER.

UPGRADING FROM v2.4.x OR EARLIER: MIMEFILTERS API Change

The API for data filters registered via MIMEFILTERS is not capability with
filters written for v2.4.x and earlier. See CHANGES and the documentation
for the MIMEFILTERS resource for the API.

If you use custom style filters written for v2.4.x, or earlier, you will
need to update them for them to work properly under v2.5, and later.

UPGRADING FROM v2.1.x OR EARLIER: Database Format Change

If you have archives created with v2.1.x, or earlier, the format of
mime-related resources is not compatible with v2.2, and later, versions.
MHonArc will reset the mime-related resources CHARSETCONVERTERS and
MIMEFILTERS to their default values. MIMEARGS will also be reset to the
default value unless you are upgrading to v2.5.8, or later, where the
MIMEARGS settings will be preserved.

To avoid the resetting of the mime-related resource if you are using
customized settings, you will need to re-specify your settings the next
time you update an archive. If you always specify your resource settings
each time you invoke MHonArc, then your settings should to still take
effect.

You can also use the mha-dbedit program to apply your settings directly
without processing the archive.

DOWNGRADING TO OLDER VERSIONS

CAUTION: Downgrading to an earlier version of MHonArc can corrupt your
         archives, especially when downgrading to an older version that
         used different database file storage formats from the current
         version in use.

Changes in archive format are not common, so downgrading can be okay
depending on the versions involved. The key versions to watch out for are
the ones noted in this section where database format changes have occured.
The following lists release numbers where a format change occured:

  • 2.0.0
  • 2.2.0
  • 2.5.0

For example, if an archive was last updated with v2.5.0, processing the
archive with a previous release will cause problems.

A possible method for successfully downgrading to a release with
differences in the database format, is to try to reconstruct the database
file using the mha-dbrecover utility contained in the MHonArc version the
archive is being downgraded to.

TIP: The safest way to downgrade is to recreate an archive from the
     original raw mail data. It is good practice to preserve the raw mail
     data for cases like this and for general archive recovering situations
     due to file corruption or other system failures.

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v2.6.9 Notes

Attachment filename format change

Attachment filenames have changed from the numeric-style <ext><#####>.<ext>
to <ext><XXXXXXXXXX>.<ext> where <XXXXXXXXXX> is a random string. For
example, a jpeg image in the older format would have a filename like
"jpg00001.jpg", and in the new style, it would be something like
"jpgAOMySzCNIE.jpg".

The change should be transparent and was done to provide support for the
ATTACHMENTDIR resource and as a performance enhancement. However, if you
perform any custom post-processing on archives that depends on the old
numeric-style format, you will need to take this change into account.

mhonarc::write_attachment: API change

mhonarc::write_attachment is the main routine for filters that save data to
an external file. The signature of the routine was changed while fixing bug
#5473. See the API appendix for more information.

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v2.6.0 Notes

m2h_text_html::filter: default argument removed

The default argument for the m2h_text_plain::filter has been removed. The
DEFCHARSET can be used instead.

SPAMMODE: Applies to message body text.

If SPAMMODE resource is enabled, it enables the new MODIFYBODYADDRESSES
resource, which enables ADDRESSMODIFYCODE to rewrite addresses in message
text bodies. If you prefer to not have addresses in message bodies modified
when SPAMMODE is enabled, you must explicitly disable the
MODIFYBODYADDRESSES resource.

readmail::MAILhead_get_disposition: API change.

The calling interface to readmail::MAILhead_get_disposition has been
changed to the following:

($disp, $file, $raw, $html_name)  =
              readmail::MAILhead_get_disposition($fields_hash_ref, $do_html);

The $file return value now has special, or invalid, filename characters
converted to underscores.

The $do_html is optional. If a true value, $html_name will be returned as a
representation of the filename suited for inclusion HTML and with character
conversion processing done.

The $raw return value is the raw filename value as specified in the message
header, which may include pathname components. This return value is mainly
for informative reasons and it should not be used by filter code for
security reasons.

The changes are backward compatible, but if you have written custom
filters, you may want to use the new calling convention if you display the
filename in the HTML generated.

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General Notes

Japanese and MHonArc

Information on using MHonArc in a Japanese locale is available at the
following location (documents in Japanese): <http://www.mhonarc.jp/>.

Auto-loaded URL attributes stripped in HTML messages

For v2.5, the default text/html filter (mhtxthtml.pl) will disable
auto-loaded URL attributes for some HTML elements -- IMG, BODY, IFRAME,
FRAME, OBJECT, SCRIPT, INPUT -- except for cid: URLs. This behavior can be
disabled if the 'allownoncidurls' filter argument is specified.

The new behavior prevents malicious URLs being used to verify mail
addresses, secretly setting cookies, or gather some statistical data
without the explicit consent of the reader.

iso8859.pl deprecated

ISO-8859 character set data processing now defaults to using the
MHonArc::CharEnt module in v2.5. The old iso8859.pl library is still
provided for compatibility with older archives, and with v2.6, iso8859.pl
directly invokes MHonArc::CharEnt.

To update archives to use the new settings, you can run the following
command,

┌─────────────────────────────────────────────────────────────────────────┐
│mha-dbedit -rcfile examples/def-mime.mrc \                               │
│           -outdir /path/to/archive                                      │
└─────────────────────────────────────────────────────────────────────────┘

where examples/def-mime.mrc represents the default MIME processing
resources for MHonArc provided within the MHonArc distribution.

NOTE: v2.5.4, and later, generated archives will automatically inherit new
      CHARSETCONVERTERS if the built-in defaults are being used. However,
      if you have defined CHARSETCONVERTERS for your archives, you will
      need to explicitly update your archives if you want the new settings
      applied to your archives.

TSLICE range setting

The value of the TSLICE resource is used to determine the number of
messages to update, before and after by thread, of each new message added.
To insure that messages within a thread slice are updated when a new
message is added, make sure the before and after ranges specified for
TSLICE is equal to the maximum-before and the maximum-after range arguments
specifed in the uses of the $TSLICE$ resource variable. For example, if you
have $TSLICE(0;4)$ and $TSLICE(3;3)$ in message layout resources, you
should set TSLICE to 3:4.

If you only use $TSLICE$ once, it is best to set options for thread slice
formatting via the TSLICE resource so you will not have anything to worry
about.

MHonArc code under the mhonarc namespace

If upgrading from v2.1.x, or earlier, any custom filters you have developed
may need to modified. If your filter accessed some main variables, your
filter will not operate properly. All variables that used to be in package
"main" are no longer. The major variables are now in package "mhonarc". For
example, $::OUTDIR is now $mhonarc::OUTDIR. See the MIMEFILTERS resource
page for more information.

HTMLEXT and MSGPREFIX usage warning

See the warnings in the documentation for the HTMLEXT and MSGPREFIX
resources before using them.

Applying new MIMEFILTERS settings

Occasionally, a new release of MHonArc may contain new MIME filters. See
the CHANGES file to check if any new filters have been added.

If you confirm that new filters have been added, and you want to apply them
to your archives, you use the mha-dbedit program using the def-mime.mrc in
the examples directory.

NOTE: v2.5.4, and later, generated archives will automatically inherit new
      MIMEFILTERS if the built-in defaults are being used. However, if you
      have defined MIMEFILTERS for your archives, you will need to
      explicitly update your archives if you want the new settings applied
      to your archives.

Example usage of mha-dbedit:

┌─────────────────────────────────────────────────────────────────────────┐
│mha-dbedit -rcfile examples/def-mime.mrc \                               │
│           -outdir /path/to/archive                                      │
└─────────────────────────────────────────────────────────────────────────┘

Change the -rcfile and -outdir pathnames to reflect where you are running
mhonarc and where your archive is located, respectively.

Note, if your archives are using custom settings of MIMEFILTERS, MIMEARGS,
and/or CHARSETCONVERTERS resources, you will need to create a variant
version of def-mime.mrc (included in the examples directory) to include
your settings and use the variant version when updating your archives.

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$Date: 2005/07/11 00:13:53 $
MHonArc
Copyright © 1997-2005, Earl Hood, mhonarc@mhonarc.org