From f1efa648c501e910f675475c522dde7ed44c671f Mon Sep 17 00:00:00 2001
From: Mitch Jackson <mitch@freeside.biz>
Date: Sun, 3 Dec 2017 23:05:13 +0000
Subject: [PATCH] RT#76877 Add an outgoing email notification blacklist

---
 rt/etc/RT_SiteConfig.pm             |  2 ++
 rt/lib/RT/Action/SendEmail_Local.pm | 63 +++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 rt/lib/RT/Action/SendEmail_Local.pm

diff --git a/rt/etc/RT_SiteConfig.pm b/rt/etc/RT_SiteConfig.pm
index 6420d11ef..e22d202e6 100644
--- a/rt/etc/RT_SiteConfig.pm
+++ b/rt/etc/RT_SiteConfig.pm
@@ -58,6 +58,8 @@ Set($MessageBoxRichTextHeight, 368);
 
 #Set(@Plugins,(qw(Extension::QuickDelete RT::FM)));
 
+# Enable blacklist for e-mail notifications (matches via case insensitive regex)
+#Set(@NotifyBlacklist,(qw(reddit.com slashdot.org frank)));
 
 # Define default lifecycle to include resolved_quiet status workflow
 Set(%Lifecycles,
diff --git a/rt/lib/RT/Action/SendEmail_Local.pm b/rt/lib/RT/Action/SendEmail_Local.pm
new file mode 100644
index 000000000..64a04dead
--- /dev/null
+++ b/rt/lib/RT/Action/SendEmail_Local.pm
@@ -0,0 +1,63 @@
+use strict;
+use warnings;
+no warnings qw(redefine);
+
+package RT::Action::SendEmail;
+
+=head1 DESCRIPTION
+
+Overlay for RT::Action::SendEmail to implement a global email notifications
+blacklist.  All components that send email using the SendEmail action will
+be affected by this blacklist.
+
+The web interface uses these filters to decide which email addresses to
+display as sendable.  This gives us the added bonus of transparency.  If
+an e-mail address is blacklisted, it will never appear in the recipient
+list on a ticket correspondance.
+
+=head1 USAGE
+
+To enable the blacklist, add a configuration option to RT_SiteConfig.pm
+
+    Set(@NotifyBlacklist,(qw(reddit.com slashdot.org frank)));
+
+If an email address regex matches any item in the list, no email is sent
+
+=head1 DEV NOTE
+
+This overlay implementation will need to be maintained if RT updates
+the SendEmail action to filter addresses differently.  The benefit of
+using rt overlays is our library changes easily persist between rt versions,
+and don't need to be reimplemented with each release of rt.  The downside
+of overlays if the underlying rt core functionality changes, our overlay
+may break rt until it is removed or updated.
+
+For information on RT library overlays,
+see L<https://rt-wiki.bestpractical.com/wiki/CustomizingWithOverlays>
+
+=cut
+
+sub RecipientFilter {
+    my $self = shift;
+
+    unless (ref $self->{RecipientFilter}) {
+      my @blacklist;
+      eval { @blacklist = @RT::NotifyBlacklist };
+      if (@blacklist) {
+        push @{$self->{RecipientFilter}}, {
+          All => 1,
+          Callback => sub {
+            my $email = shift;
+            for my $block (@blacklist) {
+              return "$email is blacklisted by NotifyBlacklist, skipping"
+                if $email =~ /$block/i;
+            }
+            return 0;
+          }
+        };
+      }
+    }
+    push @{ $self->{RecipientFilter}}, {@_};
+}
+
+1;
-- 
2.11.0