From 3e639ca78aa70ad6a6598bcf32d4b72696e3ebfb Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Sat, 2 Apr 2022 01:56:59 +0000
Subject: examples/unsubscribe.milter: RFC 8058 (List-Unsubscribe=One-Click)

This allows unambiguous signaling to some MUAs and webmail clients
that th List-Unsubscribe header contains an instantaneous
unsubscribe option.
---
 examples/unsubscribe.milter | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'examples/unsubscribe.milter')

diff --git a/examples/unsubscribe.milter b/examples/unsubscribe.milter
index 04a39761..216b0ddd 100644
--- a/examples/unsubscribe.milter
+++ b/examples/unsubscribe.milter
@@ -1,5 +1,5 @@
 #!/usr/bin/perl -w
-# Copyright (C) 2016-2021 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 use strict;
 use Sendmail::PMilter qw(:all);
@@ -96,6 +96,7 @@ $cbs{eom} = sub {
 
 		my $unsub = $priv->{header}->{'list-unsubscribe'} || [];
 		my $n = 0;
+		my $added;
 		foreach my $u (@$unsub) {
 			# Milter indices are 1-based,
 			# not 0-based like Perl arrays
@@ -114,7 +115,11 @@ $cbs{eom} = sub {
 			$v .= ",\n <https://$domain/u/$u/$list>";
 
 			$ctx->chgheader($k, $index, $v);
+			$added = 1;
 		}
+		# RFC 8058
+		$added and $ctx->addheader('List-Unsubscribe-Post',
+					'List-Unsubscribe=One-Click');
 	};
 	warn $@ if $@;
 	SMFIS_CONTINUE;
-- 
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