diff --git a/src/mimefactory.rs b/src/mimefactory.rs
index 4cee76a49..b9f724f49 100644
--- a/src/mimefactory.rs
+++ b/src/mimefactory.rs
@@ -1019,7 +1019,6 @@ impl MimeFactory {
                     | "in-reply-to"
                     | "references"
                     | "auto-submitted"
-                    | "chat-version"
                     | "autocrypt-setup-message" => {
                         unprotected_headers.push(header.clone());
                     }