diff --git a/rc/filetype/mail.kak b/rc/filetype/mail.kak
index 92c2e17ca..4cbae02ae 100644
--- a/rc/filetype/mail.kak
+++ b/rc/filetype/mail.kak
@@ -21,7 +21,7 @@ provide-module mail %{
 require-module diff
 
 add-highlighter shared/mail group
-add-highlighter shared/mail/ regex ^(From|To|Cc|Bcc|Subject|Reply-To|In-Reply-To|References|Date):([^\n]*(?:\n\h+[^\n]+)*)$ 1:keyword 2:attribute
+add-highlighter shared/mail/ regex ^(From|To|Cc|Bcc|Subject|Reply-To|In-Reply-To|References|Date|Message-Id|User-Agent):([^\n]*(?:\n\h+[^\n]+)*)$ 1:keyword 2:attribute
 add-highlighter shared/mail/ regex <[^@>]+@.*?> 0:string
 add-highlighter shared/mail/ regex ^>.*?$ 0:comment