mda|learn|watch: support dropUniqueUnsubscribe config

List-Unsubscribe headers with unique identifiers (such as those
generated by our examples/unsubscribe.milter) should not
end up in public archives.  Add a new config knob to strip
List-Unsubscribe headers if they have the
`List-Unsubscribe-Post: List-Unsubscribe=One-Click'
header.

Unfortunately, this breaks DKIM signatures if the signature
covers either of these List-Unsubscribe* headers.  However,
breaking DKIM is the lesser evil compared to any archive reader
being able to stop archival by an independent archivist.

As much as I would like this to be the default, it probably
affects few users at the moment since very few mailing lists
use unique identifiers in List-Unsubscribe (but that number
has grown, recently).

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/PublicInbox/LeiToMail.pm b/lib/PublicInbox/LeiToMail.pm
index b73af68a..0d2f586a 100644
--- a/lib/PublicInbox/LeiToMail.pm
+++ b/lib/PublicInbox/LeiToMail.pm
@@ -10,6 +10,7 @@ use PublicInbox::Eml;
 use PublicInbox::IO;
 use PublicInbox::Git;
 use PublicInbox::Spawn qw(spawn);
+use PublicInbox::Import;
 use IO::Handle; # ->autoflush
 use Fcntl qw(SEEK_SET SEEK_END O_CREAT O_EXCL O_WRONLY);
 use PublicInbox::Syscall qw(rename_noreplace);
@@ -672,6 +673,11 @@ sub _pre_augment_v2 {
                 });
         }
         PublicInbox::InboxWritable->new($ibx, @creat);
+        local $PublicInbox::Import::DROP_UNIQUE_UNSUB; # only for workers
+        PublicInbox::Import::load_config(PublicInbox::Config->new, sub {
+                $lei->x_it(shift);
+                die "E: can't write v2 inbox with broken config\n";
+        });
         $ibx->init_inbox if @creat;
         my $v2w = $ibx->importer;
         $v2w->wq_workers_start("lei/v2w $dir", 1, $lei->oldset, {lei => $lei},