What are you calling your mail boxes and your primary one?
Do you mean the folders within your email account and the Inbox or do you mean other email account ie ones with different email address to your main email account?
If it is different email accounts, you now need to log into them separately as they can not be accessed from the "drop down box" on the main account.
Try using this link to log onto the email accounts.
BTMail
If it is other email accounts you are meaning the may also have been deleted if it is over 150 days since you last used them they may have been deleted.
See link
Why has my email address been suspended or deleted? | BT Help
