download appendixes automatically

I want to know where I can set things so that all data is fully downloaded automatically so that I can work offline with all emails including appendixes.

Assuming your account is IMAP, Menu/tools/accounts click on the IMAP tab and select both "Download messages for offline use: and “Include attachments and images”.

Be aware, however, that the initial synchronization could take quite a bit of time depending on number of emails and internet speed.