How can I edit the way autodiscover.xml behaves in SBS 2008 and 2011?

Question

I have autodiscover working correctly on a few SBS 2008 and SBS 2011 servers. But, its doing its usual misbehaving. When setting up a new Outlook profile, the user enters their email address and password.  Autodiscover is successful in creating all
the account settings, but at the end of the wizard a username and password window pops up with the users full email address incorrectly filled in as the username, which is why it didn't work.
This has always been so annoying about SBS.  The user then has to be told to delete their email address in the username field, then fill in "domain\username" instead.  Only then is the authentication successful.
I've read lots about people adding the external domain UPN Suffix to ADD&T, then manually changing ever users login to domain.com instead of domain.local.   Then you have to mess with the owa authentication settings in exchange to accept the
UPN.   Its all too ridiculous.  There must be a simpler way.
I have read about how you can control how the autodiscover.xml behaves, and there are examples of how to do it in this document:
https://docs.google.com/viewer?a=v&q=cache:0jap1FNKgV0J:https://support.quest.com/Shared/Images/SOL51188_Outlook%2520Automatic%2520Account%2520Configuration.doc+&hl=pl&gl=pl&pid=bl&srcid=ADGEESjizUeFf-JYaM7ZdfIgUCKMMXtcCl0Y3pknFbuwd64GNHIEP1K8a_mpg2YIEisP6sz5DzbtVtdW4Pc42PE0Kjd6bz-3vXz0iaQm7FKi0AnwgvFG_41ZAkBLWynaJtf8s8xyi_d2&sig=AHIEtbSie1mEHTn8el4DPquNxrpovwknUQ
The document above shows the settings we need to change.  It looks like we can add the local domain using DomainName into the autodiscover.xml and this will stop autodiscover reporting that the full email address is required.  So we
should be able to get autodiscover to populate the username pop-up with with "domain\user" automatically. 
OK, so my question is, how on earth do I edit these settings in SBS 2011?  I can't find any articles that talk about how to edit autodiscover. 
If I could just edit this one setting (that Microsoft should have correctly configured in the first place) autodiscover will work perfectly for all existing users and all future users, without having to do anything.

Answer 1

Just to straighten out a few things;
1) This is NOT a bug, rather by design. Not every active directory has an exchange server in place, and MS is assuming you don't want to give your internal domain name out to people (which is why it doesn't default to domain\username)
2) Going on what I said in 1), this is NOT SBS specific this is the same way with every Active Directory/Exchange install, keep in mind Microsoft did NOT specially design the software for SBS, they just bundled it into a supported configuration in a neat
little package -since the Exchange server we run on SBS is the same Exchange server powering hundreds of hosted email providers -it makes sense why autodiscover doesn't provide the domain\username (imagine what a mess that would be!)
3) I understand it's a little bit time consuming but it can actually be done for all users in a matter of seconds, select all users, right click and go to Properties, you can then choose the UPN Suffix for all users. When a new user gets created one of the
settings in the wizard is the UPN suffix and is easily changeable as long as you notate for the person creating the user to do it. (The problem here is if you're using the SBS Console instead of AD to setup the User in which case that's just an oversight
in design not a bug in the programming)
4) You can most certainly have a powershell script that changes the UPN suffix from A to B, let me know if you're interested I'll dig one up for you. That can be run on a scheduled task and will solve the remaining issues you have :)
I do see you mentioned it in number 3, I must have missed since I didn't re-read the OP before posting the article, however I just tested on several SBS 2011 machines and OWA authentication settings don't have to be changed at all, this worked immediately
for Outlook Anywhere and Outlook Web Access in my lab and two different customer production systems.
-GreenlightTech