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  5. What to expect before, during, and after the M365 migration.

What to expect before, during, and after the M365 migration.

If you have any questions or concerns during the email migration process, don’t hesitate to contact the IT Helpdesk. Thank you for your patience and cooperation during this required transition.

Before the migration


  • All legacy college email accounts need to be migrated by summer 2024.
  • You will be notified when your mailbox is scheduled for migration. The ITS helpdesk will be available throughout the process.
  • If you want to migrate earlier for more one-on-one support or want the benefits of M365 sooner, you can volunteer for an earlier migration.
  • ITS aims to complete most mailbox migrations within five days. (Migrations typically start on a Wednesday and finish by the following Monday.)

What you should do

  1. Check your current mailbox for any attachments over 30MB and remove or backup these files, if needed. These files cannot be migrated automatically. You can download and store these files on free CUNY cloud storage tools such as Dropbox or OneDrive.

    Note: Press Shift + Delete to fully remove messages from your mailbox and the server recycle bin to ensure the deleted files aren’t included in the migration. 
  1. Clean up and organize your saved folders.
  2. Remove or locally archive any messages, folders, and attachments that you do not want included in the migration. You can connect local Outlook .pst archives after your migration.
  3. Make sure ITS knows about all the shared/entity mailboxes that you need to access and the appropriate permissions.

During the migration

Activation of Your Microsoft 365 Email Account

  • Email Routing from CUNY: Upon activation, all messages from CUNY central systems (e.g., Dropbox, Blackboard) and from any CUNY employees that already moved to M365 (including Brooklyn College employees) will be sent to your new M365 mailbox. You will be able to access your M365 mailbox on the web.
  • Email Routing from Brooklyn College and External Parties: Until your migration is complete and confirmed by ITS network support, all messages sent to your Brooklyn College email address (@brooklyn.cuny.edu) from outside CUNY and from Brooklyn College employees that have not yet moved to M365 will only be available in your old college mailbox.
  • You will need to check both mailboxes (M365 and your old legacy mailbox) during this time to avoid missing any messages. Both your local mailbox and M365 mailbox will be active during the migration period (usually 2-3 days from the start of your migration). We recommend keeping your local Outlook desktop profile in place and checking your M365 mailbox on the web at outlook.office.com (sign in with your CUNY Login). Upon completion of your migration, all email will be routed to your new M365 mailbox.
  • You can continue using your shared mailboxes the same way until the migration is complete for both your mailbox and the shared mailbox.

What You Should Do

  1. Periodically check your new M365 mailbox on the web throughout the migration process: Your new M365 mailbox will be activated at the start of your migration (starting on Wednesday). You can check your new mailbox on the web at https://outlook.office.com/mail/. (Sign in using your CUNY Login credentials.)
  2. Avoid making major changes to your local college mailbox, such as deleting or moving messages and folders, to reduce the likelihood of synchronization issues.

After the migration

  • Email redirection: Once all your saved messages and calendar events are migrated to your new M365 mailbox, you will receive a final confirmation message from ITS to your old mailbox.
  • Your old mailbox will be deactivated. After receiving the email confirmation, your legacy email account will be deactivated and you only need to check your M365 account going forward.
  • Other employees might get an undeliverable auto-response when sending you email: College employees with local college email accounts (not yet migrated to M365) might receive an undeliverable auto-response when trying to send you email if their local address book is pointing to your old mailbox. Here’s a simple solution.
  • You might get an undeliverable auto-response when sending email to employees not yet migrated. Until all college employees are migrated (summer 2024), we recommend typing the full email address (username@brooklyn.cuny.edu) when sending internal messages and not relying on the autocomplete lookups in your email editor.
  • Note: The M365 directory includes all CUNY employees (not just Brooklyn College). When searching by name, be careful to select the proper user by inspecting and confirming the username. CUNY is planning to add college codes to the directory in the future to avoid confusion.

What You Should Do

  1. Check your mailbox: Examine your new mailbox for any discrepancies and report them to the ITS Helpdesk
  2. Remove your old email profile: After receiving the confirmation email from ITS that your mailbox migrated successfuly, you can safely remove your legacy email profile from Outlook and other email clients and exclusively use your M365 account.
  3. Add your new M365 profile to Outlook and your mobile devices: Configure your email clients to access your M365 account. Contact the IT Helpdesk for assistance, if needed.
  4. Review your new mailbox: Inspect your M365 mailbox to ensure all emails, folders, and calendar events appear as expected. If you notice any issues, missing emails, or have questions or concerns, contact the IT Helpdesk immediately.
  5. Training: Familiarize yourself with some of the new CUNY Cloud and M365 features and functionalities by visiting our CUNY Cloud Productivity Tools page. Although email works the same, there are many new time-saving productivity features in M365.

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