Dear all,

we are exchange 2010 SP3 we migrate to exchange server 2013 sp1 cu7 all the mailbox migrated cannot connect to outlook client

howver, user on 2010 cannot redirect from exchange 2013 to 2010.

Greetings!  Just want to make sure I understand.  You are saying that user mailboxes migrated to Exchange 2013 cannot connect?  When you say Exchange 2010 users cannot connect to Exchange 2010 via 2013, how are they doing that?  OWA?  What does Outlook connection status indicate?

How are your 2010 clients connecting and have all records been updated to point to Exchange 2013 servers?  Do you happen to be using Outlook Anywhere internally?

Not sure if it applies to your environment but you may want to check this out:

http://blogs.technet.com/b/exchange/archive/2013/05/23/ambiguous-urls-and-their-effect-on-exchange-2010-to-exchange-2013-migrations.aspx