From 315a8869a4b1fe6071933a6ffc37e8566bd7c914 Mon Sep 17 00:00:00 2001
From: anon <anon>
Date: Thu, 18 Apr 2024 23:34:28 +0200
Subject: [PATCH] Explicitly state that the text/html body isn't
 transfer-encoded

I'm not sure this is important, but thunderbird does it too, so it can't
hurt.

Relevant: RFC 2045 Sec. 6.4:
>The Content-Transfer-Encoding values "7bit", "8bit", and "binary" all
>mean that the identity (i.e. NO) encoding transformation has been
>performed.  As such, they serve simply as indicators of the domain of
>the body data, and provide useful information about the sort of
>encoding that might be needed for transmission in a given transport
>system.  The terms "7bit data", "8bit data", and "binary data" are
>all defined in Section 2.
---
 email.d | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/email.d b/email.d
index 9dd826f..e6095a4 100644
--- a/email.d
+++ b/email.d
@@ -189,13 +189,14 @@ class EmailMessage {
 
 			{
 				MimeContainer mimeMessage;
+				enum NO_TRANSFER_ENCODING = "Content-Transfer-Encoding: 8bit";
 				if(isHtml) {
 					auto alternative = new MimeContainer("multipart/alternative");
-					alternative.stuff ~= new MimeContainer("text/plain; charset=UTF-8", textBody);
-					alternative.stuff ~= new MimeContainer("text/html; charset=UTF-8", htmlBody);
+					alternative.stuff ~= new MimeContainer("text/plain; charset=UTF-8", textBody).with_header(NO_TRANSFER_ENCODING);
+					alternative.stuff ~= new MimeContainer("text/html; charset=UTF-8", htmlBody).with_header(NO_TRANSFER_ENCODING);
 					mimeMessage = alternative;
 				} else {
-					mimeMessage = new MimeContainer("text/plain; charset=UTF-8", textBody);
+					mimeMessage = new MimeContainer("text/plain; charset=UTF-8", textBody).with_header(NO_TRANSFER_ENCODING);
 				}
 				top = mimeMessage;
 			}
@@ -1153,6 +1154,11 @@ immutable(ubyte)[] decodeQuotedPrintable(string text) {
 	return ret;
 }
 
+/// Add header UFCS helper
+auto with_header(MimeContainer container, string header){
+	container.headers ~= header;
+	return container;
+}
 
 /// Base64 range encoder UFCS helper.
 alias base64encode = Base64.encoder;