If I want to retrieve, for example, a mail user using the remoting API but I do not know its ID in the database is there a way I can get it? I know that when I call mail_user_add it returns the new ID and that I can pass this when I call mail_user_get but without storing a list of these IDs myself I can't then access/update the mail users in the future. Also, even if I did store these IDs myself I wouldn't be able to access mail users that had been added separately through the ISPConfig front end. What I need is a function similar to dns_zone_get_by_user which returns a list of zones and their IDs for a particular client. Does something similar exist for mail users? It would be useful to have such functions for all of the different configuration elements, not just mail users.