How to expunge email from the Gmail "All Mail" directory over IMAP? (with Alpine e-mail)

Looking to manually save quantities of e-mail in batches so that they're deleted and expunged from Gmail to free up space. From Alpine the error message received is: [No messages expunged from folder "[Gmail]/All Mail"] Moving these messages to Gmail/Trash will enable expunge to function correctly. Presumably this is a safety feature of Google? Preventing deletion of e-mail in the All Mail directory over IMAP would seem to be a configuration of Gmail. Aside from running dovecot and postfix, are there other suggestions? The mail as from Alpine: Dir: [Gmail]/ --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- All Mail[/] Chats[/] Drafts[/] Important[/] Sent Mail[/] Spam[/] Starred[/] Trash[/]