Our netbios and DNS domain have an underscore character in them. We are looking at doing a domain rename, but I just wanted to check to see if I have any other options. We are currently running Exchange 2003, and a root and child domain are setup. We have a lot of servers and things like SMS and SharePoint that aren't really supported for the rename either. I just can't stand the thought of a rename for just Exchange 2007. Does anyone have any advice or suggestions to this? We've run the domain rename operation in testing a few timesnow and all goes well, but I don't want to break other applications just to install Exchange 2007. I don't understand why this is a new requirement when 2003 supported it just fine.

Any luck with this? I am facing the exact same issue as you are. We are making plans to do a domain rename this weekend unless we can figure out another way. It is a pretty lame result in the name of just one character, that used to be supported! If i find anything out I will post it here. Good luck!

First of all!!! --> you cannot rename a domain after you have exchange 2007 installed. I realize this isn't exactly your intent or your situation, but just for anyone else passing through. second, check out this two page thread:http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=2814732&SiteID=17 its about single label dns domain names, but is basically the same type of issue you are describing. I would encourage you to post on the msexchangeteam site before 2/15 as they mention.

I am aware about not being able to perform a domain change after Exchange 2007 is installed. I have found that those with a single level domain havethat as a majorproblem, but they are different. 1. Why did microsoft add the restriction of the underscore in the DNS name?? We have had one since Windows NT 4. It has survived every upgrade since, NT 4 -> Windows 2000 (only change was adding .ad to the end), and then from Windows 2000 -> Windows 2003. 2. I guess we are lucky that we cannot install because we still do have the ability to perform a name change, so we are a different scenario with a similar problem. So we are left with performing a rename, which will be a nightmare, as almost every product we buy uses LDAP for single sign on authentication. But in most programs it has a hardcode of \ \ "old domain name". So we have to update 10 different peices of Software / Hardware by 80 users, just so people can log in. Or we do a transition to a new domain, but that looks like even more work, as we will still have to perform the above, + add a new domain with DCPROMO and then set up replication, move EVERYTHING, and then phase out the old domain. Lame move developers...what did an underscore ever do to you???

Here is the article that reports domain changes aren't supported with Exchange 2007. It was also in the earlier link: http://support.microsoft.com/kb/925822 Also, I was not suggesting that you have a single label domain name, but you are still essentially fighting the same fight (unsupported domain name) and I am encouraging you to read the two above pages anyway, and contribute to the forum. Microsoft listens. You have until 2/15 to post your situation. regarding #1 I'm not a DNS RFC expert, but perhaps an underscore isn't a proper DNS character? Now if you are asking "why restrict" anyway, you are definitly asking the same question as Single label domain users. 2. agreed I would rename. they are both sucky options, but i think renaming is the lesser of two evils.

I would have to say you are right about the _ not being proper. Most places I have read say that Microsoft will support it in DNS, but outside of that they don't accept it. Which is fine, BUT, e-mail doesn't need your domain to send mail, it needs DNS, and SMTP to send mail, it doesn't reference your Windows Domain in that handshake. In our case, our e-mail addresses are nothing close to our domain name. Granted Exchange does now integrate into the Domain through Active Directory, but the server has two faces, one is inward and hosts E-mail, and GAL and such. The other is outward facing to the internet. Basically they should have properly dropped support in Windows 2000 / Exchange 2000, would have made this all easier.Back then there was a domain, but it was just in NT 4. If they enforced restricted characters at the first attempt to install Active Directory with Windows 2000, a lot of this trouble could have been saved, for myself and for SLD folks. But in the end it will just be a weekend lost to perform a Domain Name Change. *sigh* I will make a post over at the other forum. I don't mean to take anything out on you, it is just frustration with the "man"!

I feel ya! It's gonna waste my weekend too if they don't come out with the SLD update. I agree they should have just disallowed this in the beginning with E2k! Good luck! But wait for the msexchangeteam.com post on the 15th. it will address SLD issues, but may include information helpful to your cause!

I am on the same boat and it really stinks! The underscore in my domain name is keeping me from upgrading to Exchange 2007, since renaming my domain is not an option for me due to issues with several critical applications. My external facing email domains have nothing to do with our Windows 2003 domain name which is only used internally. I see that Microsoft has made an exception for single label domain names but not for domains with an under_score. It looks like I may have to set up a new domain for Exchange 2007, and create resource accounts for all my users. My only concern is that I have read on some posts that this will cause problems with Public Folder permissions. If anyone has any suggestions on an alternative to renaming my domain it would be greatly appreciated..

official answer from Microsoft:"Domain Names with underscores (_) are not supported by Exchange. Please see Naming conventions in Active Directory for computers, domain, sites and OUs http://support.microsoft.com/?id=909264 for more information" Mike Crowley A+, Network+, Security+, MCT, MCSE, MCTS, MCITP: Enterprise Administrator / Messaging Administrator