1 files changed, 4 insertions, 2 deletions

diff --git a/conf.d/040_transports.conf b/conf.d/040_transports.conf
index 5a2d389..7eee901 100644
--- a/conf.d/040_transports.conf
+++ b/conf.d/040_transports.conf
@@ -27,8 +27,10 @@ remote_smtp:
 # servers to forward messages without invalidating the signature.
 # ref: https://www.spinics.net/lists/linux-media/msg138870.html
 
-.ifndef _DKIM_SIGN_HEADERS
-_DKIM_SIGN_HEADERS = In-Reply-To:Content-Transfer-Encoding:Content-Type: MIME-Version:References:Message-ID:Subject:To:From:Date:Sender:Reply-To:Cc: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive
+.ifdef _DKIM_SIGN_HEADERS
+DKIM_SIGN_HEADERS = _DKIM_SIGN_HEADERS
+.else
+DKIM_SIGN_HEADERS = In-Reply-To:Content-Transfer-Encoding:Content-Type: MIME-Version:References:Message-ID:Subject:To:From:Date:Sender:Reply-To:Cc: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive
 .endif
 
 signed_smtp: