I have been looking for a solution to this all over, but did not find one that I like.
I have an IMAP account with some folder. I want to import all of the contents of this folder into a Gmail account. Currently, only the inbox folder is imported from the IMAP account to Gmail, but not the other folders.
I found all kind of solutions in Google, none of them are really good. The closest one to work was dragging the IMAP folder to the Gmail folder in a client like Mail or Thunderbird, but it always gets stuck after a while.