A mailbox can have many folders. These include INBOX, SENT, DRAFTS, JUNK, etc.You can also create custom folders for example to archive email.Sometimes after a mailbox transfer, or when setting up email on a new email device, the folders might appear missing.This is almost always because the folders have not been synchronised.In your mail client, you can find the option to synchronise your folders and then select the folders to add. They should then appear in your mail client.