Windows 10 SendTo becomes Share

Windows 10 'Right Click/Send To' doesn't work with the Mail app that windows 10 provides.

Bad Internet Advice: download Live Essentials

The internet is recommending downloading the old 'Live Essentials'.

(https://answers.microsoft.com/en-us/windows/forum/windows_10-other_settings/windows-10-send-to-mail-recipient-error/)
Live Essentials has not received support or security updates since January 2017. Please don't do this.

Send a file with  Mail

To use the 'Modern' Mail app to send a file,

1. Right click on the file
2. Choose share instead of send to
3. Choose the mail app.

This won't help with other applications like your scanner that want to use the 'registered email client'. To do this,  download a real email program.

To use sendto, add a full fledged mail app

emClient 

http://www.emclient.com/ 

A modern looking email program with a free license for personal use.

Thunderbird

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

An aged looking but functional  free open source email program.

I would assume this issue is due to it being a Windows Universal Windows Platform app instead of a legacy mail program.

ISSUE: Firefox PDF Upload comes through as text or other

If you upload a file through Firefox, it may send the wrong mimetype for this file.

Delete mimeTypes.rdf, in the user \Application Data\Mozilla\Firefox\Profiles folder.
You may find it in extensions folder also.

Delete the files and restart Firefox and see if it works for you.

http://techblog.procurios.nl/k/news/view/15872/14863/Mimetype-corruption-in-Firefox.html

http://codeigniter.com/forums/viewthread/146338/