Bug 26705: Make Koha::Email->send_or_die handle Bcc

Koha used to rely on Mail::Sendmail for sending emails. As an SMTP
client, the library took the job of extracting Bcc headers (and removing
them) to pass them along with the recipients listed on To: and Cc: to
the SMTP protocol in the form of RCPT TO: lines. [1]

This was overlooked when we moved to Email::Stuffer/Email::Simple and
there's a different behavior, that is a design decision [2].

This patchset re-introduces the behavior from Mail::Sendmail by
overriding the send_or_die method locally (in Koha::Email) and doing the
right thing.

Unless an explicit {to} parameter is passed, it extracts the recipients
from the headers, as Mail::Sendmail does, and calls
$self->SUPER::send_or_die with the right parameters.

To test:
1. Apply the regression tests
2. Run:
   $ kshell
  k$ prove t/Koha/Email.t
=> FAIL: Bcc is not handled correctly!
3. Apply this patch
4. Repeat 2
=> SUCCESS: Tests pass! The recipients list is correct! No Bcc header
sent!
5. Sign off :-D

[1] https://metacpan.org/release/Mail-Sendmail/source/lib/Mail/Sendmail.pm#L331
[2] https://metacpan.org/pod/Email::Sender::Manual::QuickStart#Hey,-where's-my-Bcc-support

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

Koha/Email.pm

@@ -136,4 +136,38 @@ sub create {
     return $email;
 }
 
+=head3 send_or_die
+
+    $email->send_or_die({ transport => $transport [, $args] });
+
+Overloaded Email::Stuffer I<send_or_die> method, that takes care of Bcc handling.
+Bcc is removed from the message headers, and included in the recipients list to be
+passed to I<send_or_die>.
+
+=cut
+
+sub send_or_die {
+    my ( $self, $args ) = @_;
+
+    unless ( $args->{to} ) {    # don't do it if passed an explicit 'to' param
+
+        my @recipients;
+
+        # extract all recipient addresses from header
+        foreach my $header ( 'To', 'Cc', 'Bcc' ) {
+            push @recipients,
+              map { $_->as_string }
+              $self->email->header_obj->header_as_obj($header)->addresses;
+        }
+
+        # Remove the Bcc header
+        $self->email->header_str_set('Bcc');
+
+        # Tweak $args
+        $args->{to} = \@recipients;
+    }
+
+    $self->SUPER::send_or_die($args);
+}
+
 1;