@test I tested this patch and it seems to be working properly with Isis:

When disabled: http://awesomescreenshot.com/0b73oeyh94
When enabled: http://awesomescreenshot.com/03f3oeyu02

but with hathor the Mass Mail option is still visible(but does not work as expected):

http://awesomescreenshot.com/02a3of18b7

@test the patch remove the "mass-mail" by default in Isis ; so we have to edit the option to have it back.
The default behaviour is not the right one.

@hikashop-jerome yes the default should be for no change and the option should be to disable

OK, will swap the defaults in a minute.

@dimitargsg, @brianteeman, @hikashop-jerome The functionality is reversed to keep the default behaviour intact, as suggested. Thanks for making the point!
@dimitargsg The Hathor template fix is there too, pls test again.

@zero-24 changes to keep code standard done. Thanks for pointing.

@test Followed instructions and applied test. Setting was added to mail settings and I set it to disable. The mass mail was removed from templates Isis and Hathor.

This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/4747.

@test I applied the patch and it works with Isis template. The default value for the option is the right one : mass email is activated by default.

@test Now it works properly.

This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/4747.

Multiple good tests - thanks everyone - setting to RTC

@madasha we have two more CS issues:

FILE: ...la-cms/administrator/templates/hathor/html/mod_menu/default_enabled.php
--------------------------------------------------------------------------------
FOUND 2 ERROR(S) AFFECTING 2 LINE(S)
--------------------------------------------------------------------------------
  98 | ERROR | Whitespace found at end of line
 100 | ERROR | Tabs must be used to indent lines; spaces are not allowed
--------------------------------------------------------------------------------
FILE: .../joomla-cms/administrator/components/com_users/views/mail/view.html.php
--------------------------------------------------------------------------------
FOUND 1 ERROR(S) AFFECTING 1 LINE(S)
--------------------------------------------------------------------------------
 34 | ERROR | Whitespace found at end of line
--------------------------------------------------------------------------------

See: https://travis-ci.org/joomla/joomla-cms/jobs/38251859

I added some tweaks in 4e8ce96 and merged