BT Mail to Office 365 Email Migration

• Inventory BT Mail accounts, mailbox sizes, folders, aliases, and active users.
• Use mail.btinternet.com, port 993, SSL/TLS, and the full BT email address.
• Create/provision Microsoft 365 target mailboxes and assign licenses.
• Review source limits, target throttling, message-size policies, and bandwidth.
• Run a pilot mailbox before production migration.

BT Mail source

• IMAP server: mail.btinternet.com.
• Port: 993.
• Security: SSL/TLS.
• Username: full BT email address, including @btinternet.com or @btopenworld.com.
• Password: BT mailbox password.
• For bulk migration, prepare the EdbMails CSV and validate a small test set first.

Microsoft 365 target

• Create/provision target mailboxes and assign licenses.
• Use the current EdbMails OAuth-based Microsoft 365 target connection.
• Run a pilot before production migration.

• Step 1: Download and install EdbMails IMAP migration software

  • Download EdbMails and install the application on any computer running on Windows operating system.

     See a detailed list of EdbMails system requirements for IMAP migration.

    

  • Start the EdbMails application on your system.
  • Enter your registered email ID and password, then click ‘Login’. If this is your first time using EdbMails, click ‘Start Your Free Trial’ to begin with the trial version.
     Note: The EdbMails IMAP trial lets you evaluate the workflow and migrate up to 30 items from each folder. To migrate all eligible items for licensed mailboxes, purchase the required IMAP migration license.

     View current IMAP migration pricing.

    

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

    

  • Select ‘IMAP to Office 365 Migration’.

    

  • A job name is automatically assigned by default. If you want better identification, click ‘New Job’ and assign a custom name.

    

• Step 2: Connect to the source BT email server

  • To connect a single BT email account for migration, click ‘Single User / Account Migration’.
  • For this email-migration workflow, choose ‘Connect to IMAP Server’ and continue with the provider-specific IMAP settings below.
  • Click ‘Next’ to proceed.

    

  • Before starting the migration, ensure you have the required IMAP settings for your BT Mail account. These details are usually available in your BT Mail account settings or the official support documentation. Use the following information to continue with the configuration:
    • Use the current BT Mail connection settings:
      • IMAP server: mail.btinternet.com
      • Port: 993
      • Security: SSL/TLS
      • Username: full BT email address
      • Password: BT mailbox password
  • After entering the details correctly, click the ‘Login’ button to establish the connection with your BT Mail account and continue with the migration.

    

  • To connect multiple BT Mail mailboxes, select ‘Multiple (Bulk) Users/Accounts Migration’, choose ‘Connect to IMAP Server’, and click ‘Next’.
  • Then proceed by clicking ‘Next’.

    

  • Select the ‘IMAP Migration CSV File’ option to download the ‘Sample.CSV’ file, which will be saved to your local drive for future reference.

    

  • Open the sample CSV file and enter the required details, such as the email address, password, host name, and port number.

    

  • After entering the required details in the CSV file, save your changes and close the file to continue with the next steps.
  • Next, click the 'Load Modified CSV File' button, locate your updated CSV file, select it, and open it to proceed.

    

• Step 3: Select source BT email server mailboxes

  • Choose the specific mailboxes or individual folders you wish to migrate. Once your selection is complete, click ‘Next’ to continue.

    

• Step 4: Connect to target Office 365 server

  • To set up a new connection with your Office 365 account, click ‘Add New Connection’. If you’ve previously connected an account, just select it from the available list and click ‘Connect to Existing’.

    

  • Choose the desired connection options and click ‘Next’ to proceed.

    

  • Choose your preferred authentication method and click the ‘Login’ button to proceed.

    

  • Authenticate on Microsoft sign-in page.

    

  • Choose the required method to load target Microsoft 365 mailboxes. If the automatic mailbox list does not return every required target, use the supported CSV-loading option and verify the destination mailbox list before continuing.

    

• Step 5: BT email to Office 365 mailboxes mapping

  • Choose one of the available options to map the source and target mailboxes

    

  • Where supported and selected, EdbMails can assist with target mailbox creation and automatic mapping. Verify Microsoft 365 licensing and review every source-to-target mailbox mapping before starting the production migration.

    

• Step 6: Start BT email to Office 365 migration

  • Verify the mailbox mapping, then click the ‘Start Migration’ button to begin the migration process.

    

  • Click the ‘View Logs’ button to access the full migration report. The report provides detailed information, including the mailbox mapping, an overall summary of the migration, and the item count for each mailbox and folder that was migrated.

    

  • Login to your target server and verify the items.

• Verify the Microsoft 365 target

  Review migration reports and check representative folders, messages, attachments, item counts, and user access.

• Update mail DNS when ready

  If Microsoft 365 becomes the production mail service, update the required MX/DNS records only after target validation.

• Validate Outlook/client access

  Confirm Microsoft 365 sign-in and Autodiscover behavior and recreate Outlook profiles only where required.

• Retain the source during validation

  Keep the BT Mail mailbox available for the agreed transition period before decommissioning the old email service.

 For troubleshooting, check out our knowledge base articles. If you have additional questions, browse the FAQs or engage with our customer care team for personalized assistance.