Windows 10 Mail app will not open attachments

In Mail, click the Settings represented by the gear icon at the bottom
Click Manage accounts
Select your account
Click Delete this account from this device.

Restart Mail, then set it up again.

If that does not work...

Open Start > Settings > Apps > Apps & features
Scroll down to Mail
Select it
Click Advanced options
Click Reset

Restart

Check the Store for updates

Ciao,

I'm Ugo, a Microsoft Independent Advisor willing to help other Microsoft customers.

Regarding your question, could you consider reverting to 1703 until nex stable update release?

If so:

GO BACK TO PREVIOUS WINDOWS VERSION
If less than 10 days are elapsed from your upgrade, you can try the below under "Go back to your previous version of Windows"

https://support.microsoft.com/en-us/help/12415/...

If it works, please set your internet connection as metered, to avoid that update pops back up:

https://www.howtogeek.com/226722/how-when-and-w...

Please let me know if this helped somehow.

Ciao
Ugo

Thanks. It took at least six hours to download and install v 1709, and that after weeks of failed updates. I'd prefer to find a solution that would allow this version to work for me, and others who have the same problem, or wait for Microsoft to come up with a patch, rather than go down this road again.

It can't be so hard - can it?

Thanks anyway for your time.

I'm very sorry for this issue, please let me try to help you with.

Specifically, you can try to reset your Mail app:

1) Open Settings.
2) Click on Apps.
3) Click on Apps & features.
4) Select the Mail and Calendar app from the list.
5) Click the Advanced options link.
6) Click the Reset button.
7) Click the Reset button again to confirm.

If this doesn't work, you can try to uninstall and reinstall the app.

UNINSTALL MAIL
1) Open the Start menu.
2) Search for Windows PowerShell, right-click the result and select Run as administrator.
3) Type the following command on PowerShell and hit Enter:

Get-AppxPackage Microsoft.windowscommunicationsapps | Remove-AppxPackage

4) Restart your computer to complete the task.

REINSTALL MAIL
1) Open Store.
2) Do a search for “Mail and Calendar”.
3) Click the app from the result.
4) Click the Install button to reinstall the apps again.
5) Go to Start menu, open the Mail app, and complete the setup.

Another option could involve missing packages in Mail app.

1) Open Start.
2) Search for Command Prompt, right-click the result and click Run as administrator.
3) Type the following command (all in one line)and press Enter:

dism /online /Add-Capability /CapabilityName:OneCoreUAP.OneSync~~~~0.0.1.0

4) Restart your device.
5) Open Mail
6) Click the gear button in the bottom-left corner to open the Mail settings.
7) Click on Manage Accounts, and see if the Account settings are there, which indicates that the packages has been added successfully.

If the account is still having problem, another option could be deleting and readding the account again go to Mail Settings > Manage Accounts > Select the account, select Delete account from this device, and click Delete. Once the account is removed, select Add Account to add the account one more time.

Detailed instructions of the above here:
https://pureinfotech.com/reset-mail-app-windows...

Another solution could involve using another free email client, such as Mozilla Thunderbird.

https://www.mozilla.org/en-US/thunderbird/

In the meantime, please consider that here we are independent advisors but you are personally able to send your feedback directly to Microsoft:

https://support.microsoft.com/en-us/help/402156...

Please let me know.

Thanks for your further helpful suggestions.

In the end, rather than take the risk of losing my stored emails as a result of reinstallation or reset I chose to chat online with a case handler at Microsoft. Having explained I did not want to roll back to v 1703 or reset/reinstall Mail and Calendar, I allowed a remote session, in the course of which my problem resolved itself. It appeared that in the first hours since the upgrade to v 1709 the Mail app had not been recognising attachments' file extensions and therefore not calling up the relevant apps to open them. Now, it does.

Neither of us could understand why. I'm just happy the problem has gone away.

Kind regards

Happy you quickly fixed your issue!

If you do not have further questions, please mark this thread as solved.

Feel free to come back and ask whenever you want!

This works!!!!

Now if only Microsoft would fix the bug!!!!!