Two are sky email Accounts that are labeled 'Attention required'
Is there a button labelled "fix account" next to this message?
You could try updating the app from the Windows store, just in case this is the issue - but this should have automatically happened already. Try searching for "Store" in the start menu and then click the three dots "..." button in the top-right of the store app. Then select "downloads and updates". You should then see a a "get updates" button which will update any apps that need it.
Are you fully up to date with Windows update too? Start > Settings > Update & Security > Check for Updates. May be worth restarting your PC if there are any updates to be applied.
Do you have "2 factor authentication" enabled on your Sky mail account? I think Yahoo accounts have this option available, so maybe Sky Yahoo accounts do too. That may cause this problem.
I'd probably start by backing up your e-mail accounts, then remove the e-mail account from the Windows 10 mail app and re-add it again.