I know you cannot do a direct migration and I know there are code two type tools that sorta allow it with cross forest and other domains etc, but it all seems like a lot of work for 10 users. so here is my question. Can I build up a new 2012 server with AD , DNS, DHCP etc. and then install fresh on the 2012 box 2013 exchange and create new mailboxes for the AD users already there (from the 2003 AD migration) and just import the PST files that I got from doing an EXMERGE on the 2003 SBS server? Would I have to completely decommission the 2003 box before exchange 2013 is installed leaving mail in limbo for a day while all that happened?