What you can control is how far back mail is kept on the device. For an Exchange-family account (Exchange, ActiveSync, EWS or Microsoft Graph) that is a single setting, Offline emails - days to sync - Exchange accounts, under Settings | Global Settings | Offline Storage — see Offline Storage. Lowering it is the way to keep a large mailbox from filling the device.
Folder Management — Settings | Accounts | [select the account] | Folder Management — is for something different. It holds:
- Folder Operations — create, rename and delete your own folders.
- Folder Mapping — tell BlueMail which of the provider's folders to treat as Archive, Drafts, Sent, Spam and Trash. See Mapping folders to your provider.
If a folder you expect is missing altogether, it may need enabling for access on the provider's side rather than in BlueMail — see Syncing folders and labels on an IMAP account.
