--- a/sendmail/conf.c
+++ b/sendmail/conf.c
@@ -117,6 +117,7 @@
 	{ "content-length",		H_ACHECK,		NULL	},
 	{ "subject",			H_ENCODABLE,		NULL	},
 	{ "x-authentication-warning",	H_FORCE,		NULL	},
+	{ "delivered-to",	    H_FORCE,		NULL	},
 
 	{ NULL,				0,			NULL	}
 };