I've just noticed that my inbox is missing all emails on all devices between 29/03/2019 and 30/04/2020. Will BT be able to recover them for me?
If they are not showing on the BT servers when you log onto your email account using a browser, depending when they were deleted it may be too late to recover them.
See link
https://www.bt.com/help/email/bt-email--some-of-my-emails-are-missing--can-i-recover-them-