There are two ways to migrate the old emails to exchange.

Option 1: Outlook import/export

Export from Webmail:
  1. Open Outlook
  2. Go to File -> Open & Export
  3. Select "Import/Export"
  4. Select "Export to a file"
  5. Use "Outlook Data File (.pst)" as filetype
  6. Select the folder you want to export
  7. Select a path and click finish

Import to Exchange:

  1. Open Outlook
  2. Go to File -> Open & Export
  3. Select "Import/Export"
  4. Select "Import from another program or file"
  5. Select the "Outlook Data File (.pst)" filetype
  6. Select the path to the file
  7. Use "Import items into the same folder in:" <Select your Exchange account>
  8. Click Finish

Option 2:

  1. Connect to domicil.urz.uni-magdeburg.de via SSH
  2. Execute: /usr/local/bin/imapsynctool.sh