What exactly prevents you from sending photos?

In the Windows Photo App, only option is gmail.

In Thunderbird

• click on Write
• compose email
• click on 'Attach'
• locate the photo and click on Open.
• click on Send.

I know how to send from Thunderbird, but Windows 10 will not allow me to send from Windows Photo App. Thunderbird is NOT shown as an option.

Complain to Microsoft. It's their Operating System.

I'm guessing, but probably something to do with it only allows metro apps and not desktop apps...maybe ??

Microsoft are very good at ensuring difficulty if not purchasing an MS product.

I'm not using Win10, but from menory....What happens if you use the right click > Send to > Mail recipient ?

Same SHARE menu comes up with No Thunderbird Option.

- Out of curiousity: did you use Thunderbird's internal way of setting it as the default email client (as described at the bottom of the FAQ Thunderbird and Windows 7 article), or using the Windows 10 method?

- There appears to be an issue with Windows 10 and setting it up to use the Send to menu. Can you take a look at this article at answers.microsoft.com and see if that helps?