After latest Windows 10 update “Send to Mail Receipient” stopped working for people who has Microsoft Outlook as their default mail application.
Here is how you fix it…

1. Make sure that Outlook is closed (assuming your Outlook is the default mail client already).
2. Close Outlook
3. Locate the Outlook application folder in your computer…
   C:\Program Files (x86)\Common Files\system\MSMAPI\1033\ (for 64 bits version of Outlook)
   C:\Program Files\Common Files\system\MSMAPI\1033\ (for 32 bits version of Outlook)
4. Delete Msmapi32.dll file
5. Run fixmapi.exe
6. Open Outlook (Outlook will replace & register the Msmapi32.dll and then open).

Try the “Send To > Mail Recipient” again.