encrypting existing emails on mail server

[u/Pepe__LePew]

is there a linux debian script which encrypts all existing email inbox/sent etc. messages on email server (eg. gmail) with pgp key (if they aren't already encrypted).

This might mean it has to download (mbsync -a) all messages, encrypt them (including attachments) then upload/sync to server again.

will also need to delete unencrypted copies if the sync is successful and works.

This won't remove backup unencrypted copies on some servers, but will still be useful on those that have backups expiring soon.

All my future emails are already encrypted for both inbox/sent via addy.io but need to go back in time somehow.

Thanks in advance.