I am already on the user list. The difference here is directadmin is a control panel, exim can be used on its own without a control panel, ask yourself this. How many users on that exim mailing list use exim with a control panel? Directadmin has a function of sending out welcome emails, some of these welcome emails go to email addresses that are on the domain that is to be hosted on directadmin, do you think its sensible to have directadmin deliver that email locally?
If the default config is to remain the same then perhaps directadmin should be changed so it either rejects signup mails matching the domain or it does mx lookups for singup emails regardless of local or not.
If you do a search on these forums you will find a few have had problems with this scenario.
I think we should stop here, I feel bad going off topic on the thread, if you want to leave that part of config alone then thats fine with me as I said I will just edit it to suit myself.