While migrating from the Exchange 2007 to Exchange 2010 you have to follow certain steps which are:
1) Administrative Rights
2) Active Directory Permission for the new users creation (if you are creating) while migrating the data from existing exchange to new exchange.
3) While you are migrating you should also need to take care of things like Special Identification of each users when you are moving from the existing Exchange to the new Exchange
4) Even after migration (Whether it will be using a tool or manually), you need to create every user profile manually and it will ask for the outlook version.
5) You also have to take use of the cmdlet command to move the data.
6) During the move you also need to take care of the SMTP for moving purpose.
7) Proper two way routing connection.
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