From dc61f088c73d098ffe5ae1736718f63706cb240b Mon Sep 17 00:00:00 2001
From: Jake Nelson <jake.nelson@gmail.com>
Date: Fri, 9 Jun 2023 16:18:49 -0400
Subject: [PATCH] Quote Display Names which contain special characters

RFC 822 and RFC 5322 define characters which require an atom be quoted when included as a word in a mailbox.
---
 lib/message/mu-contact.cc | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/message/mu-contact.cc b/lib/message/mu-contact.cc
index acf91230..0c25b5bc 100644
--- a/lib/message/mu-contact.cc
+++ b/lib/message/mu-contact.cc
@@ -29,13 +29,20 @@
 
 using namespace Mu;
 
+const std::string rfc822SpecialCharacters  = "()<>@,;:\\\".[]";
+
 std::string
 Contact::display_name() const
 {
 	auto needs_quoting= [](const std::string& n) {
-		for (auto& c: n)
-			if (c == ',' || c == '"')
+		for (auto& c: n){
+			// RFC 822 3.3 and RFC 5322 3.2.3 defines special characters, Ascii
+			// Control (CTL) characters (0-31), DEL (127), and space as requiring
+			// quoting.
+			if (c <=31 || c >= 127 || c == ' ' || rfc822SpecialCharacters.find(c) != std::string::npos){
 				return true;
+			}
+		}
 		return false;
 	};