IMAP to Office 365 Shared Mailbox Migration

Planning is one of the most important steps before you begin your IMAP to Office 365 Shared mailbox migration. Here is a brief checklist of points to consider before you migrate.

• Remove unused mailboxes, mail items and duplicate files from the source.
• Make an inventory of items before you make the move. These should include but are not limited to the following items.
  1. User accounts, email addresses and login credentials
  2. The source and target details, browser and operating systems used
  3. Network settings, DNS configurations, MX records, firewall settings
  4. Licensing plans on your current source server
  5. Source authentication requirements and target shared-mailbox permissions.
• Determine the size of the data and number of mailboxes you want to migrate.
  1. Decide if you want to migrate everything at once (cutover migration) or plan to migrate your data in stages (staged migration).
  2. Based on the preceding factors, estimate the approximate time that may take for the migration.
• Create the required Office 365 Shared Mailboxes, configure their email addresses, and assign the appropriate Full Access / Send As or Send on Behalf permissions to the licensed users who need access.
• Ensure you have enough network capacity and bandwidth to migrate.
• Consider the throttling and message size limits on Office 365.
• Communicate the migration plan and changes to your end users and stakeholders.
• Perform a test migration before you start the actual one.
• Start the actual migration, verify the endpoints and update the MX records.
• Check for correct mail flow and configure Outlook for all the users.
• Plan for decommissioning unused apps and their settings post migration

On source IMAP server:

• Prepare the IMAP server host name, port number, email address, TLS/SSL requirement, and the authentication credential supported by the source provider.
• To migrate multiple users, download the sample CSV file from the EdbMails application and update the details such as IMAP server hostname, port number, email address, and password for each user's mailbox you want to migrate.
• For Gmail or Google Workspace, use the authentication method supported by the account and the current EdbMails workflow. Google recommends Sign in with Google where available; use an app password only where the account has 2-Step Verification, the option is available, and that workflow requires it.

   See how to find your IMAP server host name.

On Office 365 server:

• Prepare your target Office 365 tenant. See tenant roadmap for Microsoft 365.
• Ensure the users who need access to the shared mailbox have the appropriate Microsoft 365 / Exchange Online licenses. The shared mailbox itself usually does not need a separate license up to 50 GB, but Microsoft requires additional licensing for certain scenarios such as larger storage, archiving, or litigation hold.
• Before migration, create the target shared mailbox and configure the users who require access to it.
• For shared mailbox migration, create the mailbox and set the required permissions before mapping the IMAP source.
  • Create Office 365 Public folder and assign mailbox user
  • Create Shared mailboxes on Office 365 and set the correct permission
• Use the current EdbMails Microsoft 365 modern-authentication workflow and grant the permissions required by the selected connection method. Follow the automatic app-registration guide or, where required by the organization, the manual app-registration guide.
• If you have a custom email domain to which you want to receive emails after the migration, you must add and verify the domain on Office 365. Steps to add a custom domain to Office 365 and steps to add DNS records to connect your domain.
• Ensure that you meet the network and bandwidth requirements for the migration. See network and migration planning, performance factors and best practices for Office 365 migration.
• Configure Office 365 to send and receive large messages. Follow the steps to increase the message size on Office 365 to 150MB. See message size limits on Office 365 for more information.

• • Step 1: Download and install EdbMails software

    • Download and install EdbMails on your computer.

       See EdbMails system requirements for IMAP to Office 365 Shared mailbox migration

      

    • Start the EdbMails application on your computer.
    • Provide your registered email ID and password, then click ‘Login’. If you haven’t created an account, choose ‘Start Your Free Trial’ to proceed with the trial version.
      Note: The Free Trial gives you access to the primary migration features and permits migrating up to 30 items per folder. To migrate without the trial limit, purchase a valid IMAP Migration license from the EdbMails website.

       Click here to purchase a license from the EdbMails website.

      After completing the purchase, close the application and relaunch it. Sign in using the same email ID and password used at the time of purchase to activate your license.

      

    • Select the option ‘IMAP (Gmail, Outlook & more) Migration’

      

    • Select ‘IMAP to Office 365 Migration’.

      

    • Use the default job name to proceed, or select ‘New Job’ if you want to change the name before continuing.

      

  • Step 2: Connect to Source IMAP Server

    • To set up a single user account, choose ‘Single User / Account Migration’, select the required option like ‘Connect to IMAP Server’ or ‘Connect to POP3 Server’, and then click ‘Next’ to move forward.

      

    • For a single-user login, choose the IMAP host name from the available list or enter it manually. Provide the IMAP email address and the authentication credential required by that provider. For Gmail or Google Workspace, use an app password only where the Google account policy permits it and the current EdbMails workflow requires it.
    • Then, click the ‘Login’ button.

      

    • To migrate multiple IMAP accounts at the same time, choose ‘Multiple (Bulk) Users/Accounts Migration’ and then click ‘Next’ to continue.

      

    • Select ‘IMAP Migration CSV File’ and choose the file location from your local drive.

      

    • Open the CSV file and enter the required details for each mailbox, such as the email address, password, IMAP server hostname, and port number.

      

    • Once you've finished updating the CSV file with the required information, save and close it.
    • Then, click the 'Load Modified CSV File' button, open the CSV file.

      

    • Verify the mailboxes before proceeding and click ‘Next’.

  • Step 3: Select Source IMAP Server Mailboxes

    • Select Source ‘mailboxes’ or ‘folders’ to migrate, then click ‘Next’.

      

  • Step 4: Connect to the Target Office 365 Server

    • Click ‘Add New Connection’ to create a new connection to the target Office 365 account. If you prefer to continue with a previous connection, choose it from the list and click ‘Connect to Existing’ to proceed.

      

    • Select the ‘Connect to Primary/Shared Mailboxes’ option to connect to the target Office 365 shared mailboxes, then click ‘Next’ to continue.

      

    • Select the suitable target connection method based on the modern authentication methods
    • Then, click the ‘Login’ button to continue.

      

    • Sign in through Microsoft’s secure login portal for safe and seamless authentication.

      

    • Select one of the methods to load the mailboxes. You can Select ‘Load Mailboxes Automatically’, 'Load Mailboxes using .CSV file' or ‘Load Mailboxes from previous list’ and click ‘Next’.
    • Because of Microsoft API restrictions, the application can automatically fetch only up to 100 mailboxes. If your environment contains more than 100 mailboxes, import the remaining ones using a CSV file and then click ‘Next’ to proceed.

      

  • Step 5: Map Source and Target Mailboxes

    • Choose the required mailbox mapping option

      

    • EdbMails can automatically map source IMAP mailboxes to matching Office 365 Shared Mailboxes where the available mailbox identifiers align. Review the mapping before migration and adjust source-to-target assignments manually whenever required.

      

  • Step 6: Start IMAP to Office 365 shared mailbox migration operation

    • After mapping the mailboxes, click the ‘Start Migration’ button and initiate the migration process.

      

    • Click the ‘View Logs’ button to see the IMAP migration report, which provides a detailed summary of the process, including the total number of items migrated and a folder-wise item count.

      

• Step 1: Update DNS records (MX record) to point to Office 365

  Update your MX records in your DNS to start receiving messages on Office 365. This switch ensures smooth email operation with your newly migrated server. Additionally, set up the Autodiscover record for the Outlook connectivity to the migrated mailboxes.

• Step 2: Verify shared mailbox permissions and user access

  Confirm that the required users have Full Access and the appropriate sending permissions for the shared mailbox. Verify that the shared mailbox appears in Outlook or Outlook on the web and test read, reply, and send-as behavior before closing the migration project.

  For common migration issues, check the knowledge base articles. To learn more about EdbMails IMAP Migration software and its features, visit the frequently asked questions section or contact our support team.