For customers with IONOS Mail Basic and IONOS Mail Business mailboxes.

In this article you can learn more about migrating e-mails from IONOS Mail Basic and IONOS Mail Business mailboxes (IMAP) to Microsoft 365.

Please Note

To learn how to prepare for migration, see the article Preparing IONOS Email Accounts to Migrate to Microsoft 365. Take note that all of the preparation steps must be completed first.

Restrictions regarding the import

  • The maximum size of an e-mail must not exceed 35 megabytes.
  • A maximum of 500.000 elements can be transferred per user mailbox.
  • Only e-mails will be migrated, no contacts, tasks, etc.

Getting ready for the migration

To transfer the user data of the IONOS mailboxes to Microsoft 365:

  • Open any program that allows you to create comma-seperated CSV files, e.g. Microsoft Excel.
  • Enter the following headings per column in the first line: EMailAddress, Username, Password 
  • Add a line with the user data for each user mailbox.
  • Save the file in CSV format (separator: comma).

Performing the migration

  • The users to be imported must already be created in Microsoft 365.
  • As of the beginning of 202, Microsoft has changed the design of the Exchange Admin Centre. The following step-by-step instructions refer to the menu structures and options of the classic display.
  • Log in to your Microsoft 365 administrator account.
  • Select the Admin icon in the left menu. The Microsoft 365 Admin Centre opens.
  • Select Exchange in the left menu. Note that you may have to display the menu with Show All completely.
  • Click on the Classic Exchange Admin Centre button to find the correct menu structures and options for the following steps.
  • Under Recipients, click Migration.
  • Click the ... button and select Migration Endpoints. The Migration Endpoints window opens.
  • Click on the plus  symbol to create a new migration endpoint. The Migration Endpoint Assistant window now opens.
  • Select the Migration Endpoint IMAP and click Next.
  • In the IMAP server field, enter and confirm the entry with Next.
  • In the field Migration endpoint name, enter the desired name of the migration endpoint and click New.
  • Close the Migration Endpoints window.
  • Click on the plus symbol and select Migrate to Exchange-Online. The New Migration Batch window opens
  • Select the IMAP migration item and load your prepared CSV file.
  • Complete your entry with Next.
  • Enter a name of your choice in the Name of new migration batch field and click Next.
  • To start the migration, click New. You can now close the Exchange Admin Centre. The migration process continues in the background.

You have migrated your e-mails from IONOS Mail Basic respectively. IONOS Mail Business to Microsoft 365.