Although I see all your points here this is Linux right? It's open software and we can do what we want without permission from "Mr Microsoft". I am not asking to change the name of root, just the name of a standard Linux user that could be anything. I think it makes sense for SME because in my 20 years or so of tech (mainly for small and medium businesses) I have seen the email addresses like accts, admin, sales, billing, info, contact, support, reception, etc used over and over again. Why would you use a common email address as the name for the administrator of a mail server? For example Wordpress uses wp-admin which can be renamed to anything. Even "administrator" would be a less likely hit than admin IMHO.
I also find it hard to believe that this is "hard coded". This is open software isn't it? I would be willing to make this change myself if I could get some help with it, but for now I just need keep my boss and my users happy. You are right I chose SME server and I chose it because its nice and clean and stable in my experience.
So back to the point, I am thinking of going back to using my real domain as primary to get out of this dirty mess that affects everybody on the domain. I want to go with Janets first suggestion which was to use the mailsorting contrib to send the system mails to another user. Does anybody know of any reason not to do this? I see it uses procmail or maildrop, is there any overhead using these programs or does SME already do this?