The best way to migrate Exchange mailboxes to Office 365 is to use an automated solution that would easily migrate from Exchange to Office 365 mailboxes. One tool that does this and offers numerous other exclusive features is Shoviv Office 365 Migration Tool.
Feature of this tool-:
• It swiftly migrates the numerous numbers of mailboxes with no limitation on size.
• Options to preview added source mailboxes and filter according to the message class and Item date are also embedded within the software.
• Mapping option for the source mailbox with target mailbox and search option to search source mailbox is also provided in the software.
• Facilitates to migrate Live Exchange/Office 365 Public folders and Archive mailboxes into another Live Exchange/Office 365 public folders and Archive mailboxes.
• A Free demo/trial version of the software is also available to check its working efficiency and functioning. It allows the migration of the first 50 items per folder.
For more info - Exchange to Office 365 Migration
