Although in "Settings> Account Settings" it is possible to choose an "external" memory (SD card) as the storage location, the storage location on Android 8 is left on the internal storage.
BUT: NOTHING CANNOT BE STORED ON THE INTERNAL STORAGE ALSO: An error message sais, the memory is too small for an attachement of about 400 B only (although around 1.2 GB are free).
What can I do?