Given a mail message with '\n' as linesep, generated AAR header ending line separator is '\r\n', which is incorrect. E.g.:
headers == [
b'ARC-Seal: i=1; cv=none; a=rsa-sha256; d=test1.10-69-41-116.qa.plesk.tech;\n s=default; t=1704968826;\n b=Y2giO87gPbvgBD8YkfBbkNqo457OOWj6ciSEUf1P/GBQZYt42aJyO2d5S7mfWMVYBb1ze\n 7w1CuV8Rgx6tDtvgLcNTOp8vTIUU9T4e/TL6oFnLAOT6RRxoNRWJE+kVWZKqJNy3Hb04aFI\n Pba/BqfQvtbtwjsTnYRaVXn0sFPzvKjUqpddkSFGMjdI96apKpvwGa2I9UWgB0pf5cLpRA3\n GEmS5HfiHcnNa/vq2fp41z7M+D93aMcGhbrz/dXG9V4jt0LCaw6TaZ9S1h5EpycG8pOUsO/\n 1XHBCTZMZ/E14eANQbgML2KfoMr48BUS6YzJifHHPIYY42DL9zouxWBT2qEQ==\n',
b'ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed;\n d=test1.10-69-41-116.qa.plesk.tech; s=default; t=1704968826;\n h=mime-version : date : from : to : subject : message-id :\n content-type : content-transfer-encoding : from;\n bh=AFt2xXGk+vwhUXqU7UsgrZsQKCEGq4uk03cx+GaLyeU=;\n b=ULpRCK1iPfOAYWuCrmFaWrJxzrjH4cLBcFnSs2Zhf6SnQ4rVl3TJR5Zgn7OLD10/wqokG\n q/w4agj0iWioBICZQ+TKIibp7NSwkqHqkIxwv+OeWW0HbInS/7LxOTZK4TcH6t6G9/cMiza\n Fz/TOk6bP1BuKeXgU8WjX38wyA2x3J+UmO7r2l0bGXuexOANtFWVRuO8kwRlp2a32nyAIoX\n Xqhu2OBQAA+BtvCgT5CXfYlvDZ+jNDURj2kR+OXdkVbDrSJJKAOkzQ5qp1imt62r/8wa3WG\n om+fz/1ShbMK1eOqWbyYf5Oz8eXICGFQNo52bDJ8ZWifNuDz9lHcmsIi/6Lw==\n',
b'ARC-Authentication-Results: i=1; 10-69-41-116.qa.plesk.tech; dmarc=pass (p=QUARANTINE sp=NONE) smtp.from=test1.10-69-41-116.qa.plesk.tech header.from=test1.10-69-41-116.qa.plesk.tech;\n dkim=pass header.d=test1.10-69-41-116.qa.plesk.tech;\n spf=pass (sender IP is 127.0.0.1) <email address hidden> smtp.helo=webmail.test1.10-69-41-116.qa.plesk.tech\r\n'
]
message[:80] == b'Return-Path: <email address hidden>\nX-Original-To: mail1@test1'
When assembling the resulting message this produces headers with inconsistent line separators. This, in turn, results in certain clients (such as Outlook) incorrectly displaying the message (showing headers instead of / in addition to body).
Library version: dkimpy==1.1.5
This is fixed with the following patch:
--- dkim/__init__.py.orig 2024-01-11 10:31:46.157334161 +0000
+++ dkim/__init__.py 2024-01-11 10:43:07.247551542 +0000
@@ -1120,8 +1120,7 @@
arc_headers = []
# Compute ARC-Authentication-Results
- aar_value = ("i=%d; " % instance).encode('utf-8') + auth_results
- if aar_value[-1] != b'\n': aar_value += b'\r\n'
+ aar_value = ("i=%d; " % instance).encode('utf-8') + auth_results.rstrip() + self.linesep
new_arc_set.append(b"ARC-Authentication-Results: " + aar_value)
self.headers.insert(0, (b"arc-authentication-results", aar_value))
