select {
	case <-ctx.Done():
		// Returning error here is too noisy.
		return nil
	case c.outQueue <- msg:
		return nil
	}
}

// queueMsg queues a message, with an optional payload.
// sender should not reference msg.Payload
func (c *Connection) queueMsg(msg message, payload sender) error {
	// Add baseflags.
	msg.Flags.Set(c.baseFlags)

### Existing object replication