Log Message:
Update to 2.6.0. From the announcement message:

This is a new release of the filter which adds a number of new features
and fixes a number of minor bugs.  Of particular interest is support for
the proposed DKIM reporting mechanisms introduced in the revised
"feedback-report" and new "dkim-reporting" IETF drafts.

The formal release notes entry:

2.6.0           2008/06/11
        Remove "signaturemissing" as an old-style configuration action
                as it has been superseded by "ASPDiscard" and related
                functions.
        Add "SendASPReports" configuration option which generates ASP \ 
failure
                reports if requested by the sending domain.
        Update report generation for verification failures to use the
                new Abuse Reporting Format (ARF) and DKIM Reporting
                draft proposals.
        Add "MustBeSigned" configuration option, requiring signatures to
                cover specific headers if present.
        Rename "UseASPDiscard" to "ASPDiscard".
        Add "ASPNoSuchDomain" configuration option which rejects mail that
                appears to come from nonexistent domains as reported by the
                Author Signing Practises check.
        Add "ReportAddress" configuration option, used for defining the
                From: header of reports mailed out.
        Yet another compatibility fix with respect to Sleepycat DB.
        Fix processing of "LogWhy" configuration parameter.  Problem noted
                by Erik Lotspeich.
        Add "-n" command line flag which parses the command line arguments
                and configuration file(s), then exits with an appropriate
                status code.
        Report DKIM and ASP results separately via the same
                Authentication-Results header field.  Previous versions would
                alter the DKIM result based on ASP.
        Fix bug #SF1976931: Restore function of "nosignature" old-style
                action configuration, connected to "AlwaysAddARHeader".
                Problem noted by Lucas Brasilino.
        Feature request #SF1940233: Add "DontSignMailTo" configuration \ 
option,
                allowing a list of recipient patterns whose mail should not
                be signed.  Requested by Don Hughes.
        LIBDKIM: Rename dkim_reportinfo() to dkim_sig_getreportinfo(),
                and add dkim_policy_getreportinfo().
        LIBDKIM: Add several more signature error codes covering various
                key-related errors.
        LIBDKIM: Add dkim_sig_hdrsigned() utility, DKIM_OPTS_MUSTBESIGNED
                option, and DKIM_SIGERROR_MBSFAILED error code.
        LIBDKIM: Fix a bug in the computation of the result for
                dkim_canon_minbody().
        LIBDKIM: Report corrupted base64 chunks instead of quietly
                tolerating them.
        LIBDKIM: Tidy up the cleanup code in dkim-canon.c.
        LIBDKIM: Properly handle "tag=" at the end of a data set (i.e.
                the tag exists and has an empty value).
        LIBDKIM: Use larger unsigned data types in dkim_sig_future() as
                was done elsewhere.
        LIBDKIM: Always populate a DKIM_SIGINFO with domain and selector
                before there's an opportunity for other parsing
                short-circuits.
        LIBDKIM: Fix bug #SF1984685: Remove the "margin" parameter from
                dkim_getsighdr(); make it controlled by a new function,
                dkim_set_margin(), so that the signed copy and the
                user-requested copy are identical.
        Activate _FFR_AUTHSERV_JOBID.