Thanks for posting on the Community Forums. I'm sorry to hear that you haven't been able to receive any emails from Tesco bank recently, that's really odd.
We aren't able to view mail filtering set up for your account on our end, however you can check your spam filtering rules from your end. We have a page set up here with information on how we prevent spam, and how you can remove/set up rules to control what emails are sent where in your mailbox. I know that the emails are not being sent to your spam folders, however I would still recommend taking a look at your settings.
Would you be able to find out the exact error that Tesco Bank are receiving when they try to email you?
Also, I know this may seem obvious and they've emailed you before, but do they definitely have the correct email address?