Mail App Error 0x80070490, Mail app won't sync on multiple win 10 machines.

Hi,

I understand that you are facing sync issues with Mail app. We will help you to resolve the issue.

I suggest you to follow the below methods and check if it helps.

Method 1: I suggest you to run the app troubleshooter from the below article and check if it helps.

Run the troubleshooter for Windows apps:
http://windows.microsoft.com/en-us/windows-10/run-the-troubleshooter-for-windows-apps 

Method 2: If you are accessing your account through the Windows Mail app, then refer to the following article and check if it helps.

Resolve Sync issues in Mail and Calendar apps in Windows 10. 

https://support.office.com/en-us/article/Resolve-Sync-issues-in-Mail-and-Calendar-apps-in-Windows-10-0dd86c69-18f3-4f73-9d3d-375bdc9c3e34

Please get back to us with an update on this issue, we will be happy to help.

Thank you

My apologies, I thought I had replied to this the day after posted.  The windows trouble-shooter did not provide any answer.  As mentioned, this occurs on three different machines so it is hard to imagine the same thing happened on all three.  Particularly because one of them didn't exist until after the issue started.  The other is that the app itself was working as other accounts added to the app did not experience the issue.

I cannot remove the account and reinstall as recommended in the second option as there is no option.  Apparently if the Microsoft account is primary, then it can't be removed, so this is a solution proposed without understanding how the mail app works.

The privacy switches are already at the suggested positions.  I had actually tried these before posting, but I re-examined to double-check.

However, today, after about 10-days of not working, the account seems to be syncing again, at least on one machine.  I will check the others. as I said, other accounts have not experienced the issue so it is definitely something with syncing MS accounts in the mail app.  Surprisingly gmail, and exchange work without issue.

Hi,

Try this

Press "Windows key" + R

-Type “Regedit” and press Enter
-Browse to the following path in RegEdit:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders

Right click on “AppData” and Modify it to:

%USERPROFILE%\AppData\Local

  
Press OK
Restart your PC