I would like to know if it's possible to sync mail attributes with Migration Manager for AD in target domain because i use ad sync with office 365?
Yes it is possible to sync mail attributes. It would require a Custom Add-in. Please contact your account manager and inquire.
Yes, you can use the file SyncExchangeRelatedAttibutes.xml, this file you can add how a CUstom Add-in and for default contain only ProxyAddresees in the example, this file is in Program Files (x86)\Quest Software\Migration Manager\Active Directory.