Hi, Want to upgrade our environment to Exchange 2010. We have: Exchange 2003 sp2 - single box providing mailbox and OWA Forest & Domain at 2003 fundtional level Most of the articles re transitioning involve a front end OWA server for both 2003 and 2010, I have neither. My goal is to introduce 2010 [hosting all 3 main roles], transistion users to the new mail server all whilst still providing OWA 2003 and OWA 2010. Are there any articles that cover this exact situation?

How many users do you have? You may be able to move them all over a weekend and point the existing OWA URL to the CAS once you've moved the mailboxes.Neil Hobson, Exchange MVP

Hi, We have 950 users, circa 100 with 2GB mailboxes and 300 with 1.5gb mailboxes. I have heard that a 1gb mailbox can take at least an hour to transistion. Ideally I would like to complete the transistion in one weekend of all users to the new exchange box. Thanks

I always used to work on somewhere between 2-5GB per hour in E2K3 days but things can be improved with multi-mailbox moves in E2K7\E2K10 where you can move more than 4 at a time, although you'll reach a max at some point. You could probably do 950 over the weekend but the target server will have a lot of transaction logs generated on it, so keep an eye out for those and clear them as needed. I guess you could consider a temporary E2K10 OWA URL for use until you can swing the normal URL across. Or stand up a temporary E2K3 front-end server of course.Neil Hobson, Exchange MVP

Hi, Thanks for the reply. Can yo confirm that I can do either of the following: a) Transistion users over a weekend to the new box OR b) introduce a temp Exchange 2003 OWA front end and transistion users across gradually [i.e. one month] If I understand correctly what I can not do is have one Exchange 2003 box [mailbox and OWA role] and an Exchange 2010 [holding the 3 main roles] and transistion users gradually. Thanks again, Fizzmo

Hi, You can do the item a) Transition users over a weekend to the new box. It would be better not to go on a big bang approach (multi-mailbox move), do it in a gradual manner. Let me know the progress. regards, LRMCP

If you have one more public ip with you then by using legacy host name url you can access your exchange server 2003 mailboxes through exchange server 2010 outlook web app.

Hi guys Thanks for all the replies. Just finished the Exchange 2010 course so the way forward is much clearer now. Will be a slow migration [just can't do all the users in one weekend], good news is that I can use the existing 2003 [no temporary front end needed] and let the Exchange 2010 CAS do the internal OWA redirection. Thansk again