--- a/src/doveadm/doveadm-settings.c	Fri Sep 22 14:08:45 2017 +0300
+++ b/src/doveadm/doveadm-settings.c	Fri Sep 22 13:30:43 2017 +0300
@@ -74,6 +74,7 @@
 	DEF(SET_STR, dsync_features),
 	DEF(SET_UINT, dsync_commit_msgs_interval),
 	DEF(SET_STR, doveadm_http_rawlog_dir),
+	DEF(SET_STR, dsync_hashed_headers),
 
 	{ SET_STRLIST, "plugin", offsetof(struct doveadm_settings, plugin_envs), NULL },
 
@@ -96,6 +97,7 @@
 	.dsync_alt_char = "_",
 	.dsync_remote_cmd = "ssh -l%{login} %{host} doveadm dsync-server -u%u -U",
 	.dsync_features = "",
+	.dsync_hashed_headers = "Date Message-ID",
 	.dsync_commit_msgs_interval = 100,
 	.ssl_client_ca_dir = "",
 	.ssl_client_ca_file = "",
@@ -181,6 +183,10 @@
 	fix_base_path(set, pool, &set->auth_socket_path);
 	fix_base_path(set, pool, &set->doveadm_socket_path);
 #endif
+	if (*set->dsync_hashed_headers == '\0') {
+		*error_r = "dsync_hashed_headers must not be empty";
+		return FALSE;
+	}
 	if (*set->dsync_alt_char == '\0') {
 		*error_r = "dsync_alt_char must not be empty";
 		return FALSE;