I had been using the Windows Mail app in Windows 10 for around a month, without issue, when abruptly it began to tell me my account settings were out of date. I was given an option to fix or dismiss said problem. When I opted to fix it, I was told to enter the correct password for the accounts (cantab.net and icloud.com) which had both previously been functional. I made no changes to the accounts themselves or the settings of Windows Mail, and am able to access both accounts via a browser without issue.
When I reenter the correct password for either account, I'm given the same error message a number of times before being shown the 'current password' and asked to update it. The 'current password' is shown as 16 asterisks. I have never entered a 16 digit password - mine is 9 characters. I have not changed the password requirement for either account, yet Windows Mail will not accept the correct password and always eventually returns to showing me the 'current password' at 16 characters.
Please help - it's incredibly annoying.