Update runtime files.
diff --git a/runtime/syntax/mail.vim b/runtime/syntax/mail.vim
index ed7ca21..cf4a2c6 100644
--- a/runtime/syntax/mail.vim
+++ b/runtime/syntax/mail.vim
@@ -40,7 +40,7 @@
syn region mailHeaderKey contained contains=mailHeaderEmail,mailEmail,@mailQuoteExps,@NoSpell start="\v(^(\> ?)*)@<=(to|b?cc):" skip=",$" end="$"
syn match mailHeaderKey contained contains=mailHeaderEmail,mailEmail,@NoSpell "\v(^(\> ?)*)@<=(from|reply-to):.*$" fold
syn match mailHeaderKey contained contains=@NoSpell "\v(^(\> ?)*)@<=date:"
-syn match mailSubject contained "\v^subject:.*$" fold
+syn match mailSubject contained contains=@NoSpell "\v^subject:.*$" fold
syn match mailSubject contained contains=@NoSpell "\v(^(\> ?)+)@<=subject:.*$"
" Anything in the header between < and > is an email address