Q: Mail and FB extensions is Grayed out in Photos

Try the fix in this support document:  See the link below:

If Share options or Markup is missing after upgrading to OS X Yosemite or El Capitan - Apple Support

Open the link and copy and paste  the Terminal command exactly as it is into the Terminal window, don't try to type it yourself.

It is a harmless command, but spelling errors in the Terminal can be dangerous.

This command does the following: It will reset the launch services database, so the installed applications and the services, document types, etc. supported by the applications can be found.

Paths are searched for applications to register with the Launch Service database.

Valid domains are "system", "local", "network" and "user". Domains can also be specified using only the first letter.

  -kill     Reset the Launch Services database before doing anything else

  -seed     If database isn't seeded, scan default locations for applications and libraries to register

Re: Have MacBookPro late 2013 - upgraded to ElCapitan and Photo.  Now I can not send photos to those on my contact list in Mail.  Worked fine with iPhotos and Yosemite.  What is wrong? What must I do to be able to use Mail to send pictures?