Some servers store all folders as subfolders of INBOX, e.g. the Drafts folder is INBOX/Drafts. This is a technical thing that users should not see preferably.
On one such account
isync/mbysnc with a minimal config of
will create a "flat" structure (if you don't specify the
Inbox path then your Inbox will go to
~/Maildir and all the other folders will go to
~/.mail/imaptest and any further nesting is done as expected). I do not know how isync knows this. Maybe it automatically flattens any subfolder within inbox?
commit 626d118 adding
folder-mapallows for a workaround although I can't see a way to do this automatically for all folders cf this folder-map.