--- a/src/lib/connection.c	Mon Feb 12 12:28:37 2018 +0200
+++ b/src/lib/connection.c	Sat Feb 10 09:55:43 2018 +0100
@@ -120,6 +120,27 @@
 	return conn->list->v.input_args(conn, args);
 }
 
+void connection_input_halt(struct connection *conn)
+{
+	if (conn->io != NULL)
+		io_remove(&conn->io);
+}
+
+void connection_input_resume(struct connection *conn)
+{
+	const struct connection_settings *set = &conn->list->set;
+
+	if (conn->io != NULL)
+		return;
+	if (conn->from_streams || set->input_max_size != 0) {
+		conn->io = io_add_istream(conn->input,
+					  *conn->list->v.input, conn);
+	} else {
+		conn->io = io_add(conn->fd_in, IO_READ,
+				  *conn->list->v.input, conn);
+	}
+}
+
 static void connection_init_streams(struct connection *conn)
 {
 	const struct connection_settings *set = &conn->list->set;
@@ -139,9 +160,6 @@
 			conn->input = i_stream_create_fd(conn->fd_in,
 							 set->input_max_size, FALSE);
 		i_stream_set_name(conn->input, conn->name);
-		conn->io = io_add_istream(conn->input, *conn->list->v.input, conn);
-	} else {
-		conn->io = io_add(conn->fd_in, IO_READ, *conn->list->v.input, conn);
 	}
 	if (set->output_max_size != 0) {
 		if (conn->unix_socket)
@@ -153,6 +171,7 @@
 		o_stream_set_no_error_handling(conn->output, TRUE);
 		o_stream_set_name(conn->output, conn->name);
 	}
+	connection_input_resume(conn);
 	if (set->input_idle_timeout_secs != 0) {
 		conn->to = timeout_add(set->input_idle_timeout_secs*1000,
 				       connection_idle_timeout, conn);
@@ -169,8 +188,8 @@
 	const struct connection_settings *set = &conn->list->set;
 
 	if (set->input_max_size != 0 && conn->io != NULL) {
-		io_remove(&conn->io);
-		conn->io = io_add_istream(conn->input, *conn->list->v.input, conn);
+		connection_input_halt(conn);
+		connection_input_resume(conn);
 	}
 }
 
@@ -246,6 +265,7 @@
 
 	conn->list = list;
 	conn->name = i_strdup(name);
+	conn->from_streams = TRUE;
 	conn->fd_in = i_stream_get_fd(input);
 	conn->fd_out = o_stream_get_fd(output);
 
@@ -265,10 +285,9 @@
 	o_stream_set_no_error_handling(conn->output, TRUE);
 	o_stream_set_name(conn->output, conn->name);
 
-	conn->io = io_add_istream(conn->input, *list->v.input, conn);
-	
 	DLLIST_PREPEND(&list->connections, conn);
 	list->connections_count++;
+	connection_input_resume(conn);
 
 	if (list->v.client_connected != NULL)
 		list->v.client_connected(conn, TRUE);

--- a/src/lib/connection.h	Mon Feb 12 12:28:37 2018 +0200
+++ b/src/lib/connection.h	Sat Feb 10 09:55:43 2018 +0100
@@ -100,6 +100,7 @@
 
 	unsigned int version_received:1;
 	unsigned int unix_socket:1;
+	unsigned int from_streams:1;
 };
 
 struct connection_list {
@@ -127,6 +128,8 @@
 void connection_disconnect(struct connection *conn);
 void connection_deinit(struct connection *conn);
 
+void connection_input_halt(struct connection *conn);
+void connection_input_resume(struct connection *conn);
 void connection_streams_changed(struct connection *conn);
 
 /* Returns -1 = disconnected, 0 = nothing new, 1 = something new.