How do I download my emails for offline use?

How do I download my emails for offline use?

Simply right click on the email folder which you wish to download all your messages from; and in the context menu select Properties -> Off-line.

You can choose to download only the text messages or to also include the attachments. Click “Download now” to start downloading.

That’s clear but what in case of more complicated folder structure to do it one by one is really not handy