I have 2- exch 2010 servers at remote sites. My main site has exch 2007. They are all on 1 domain. Each server has its own url to connect to owa/ smartphone etc. All was working well until I set up a new 2010 server in the the main AD site where 2007 is and tried setting it up to co-exist, changing all the url's etc to legacy.domain.com and the new exch10 to mail.domain.com. Everything is working fine for users on all 4 servers except random users are getting prompted for id and pass and outlook anywhere doesn't seem to work anymore, so users in remote sites that are off the network find that they can't get to their email.
I tried changing Set-OutlookProvider EXPR -CertPrincipalName msstd:mail.domain.org ( as well as EXCH and WEB) but that didn't seem to help. Any suggestions. Our email filters through a spam filter and I know you are supposed to update your main internet facing cas first, but that did not happen.