[filipponeri20]

Thanks a lot @sharebophar for your solution. I had to do a little of adjustment but it was right on the spot!

PROBLEM:
buddypress nouveau not sending activation email but buddypress nouveau sending correctly emails to user for notifications on manually activated users. So in my case the problem was ONLY that the validation email was not sent. I say ‘only’ from a technical perspective but from the user perspective was a VERY BIG issue. Again thanks @sharebophar for your solution
Also note that I am not running a wordpress multisite.

SOLVED:
Here are the steps I have employed:

STEP 1
a) browse to “/bp-core/bp-core-functions.php” in buddypress plugin directory
b) replace the code for ‘core-user-registration’ and ‘core-user-registration-with-blog’ with the following one

	'core-user-registration' => array(
			/* translators: do not remove {} brackets or translate its contents. */
			'post_title'   => __( '[{{{site.name}}}] Activate your account', 'buddypress' ),
			/* translators: do not remove {} brackets or translate its contents. */
			'post_content' => __( "Thanks for registering!\n\nTo complete the activation of your account, go to the following link: <a href=\"{{{activate.url}}}\">{{{activate.url}}}</a>", 'buddypress' ),
			/* translators: do not remove {} brackets or translate its contents. */
                        'post_excerpt' => __( "Thanks for registering!\n\nTo complete the activation of your account, go to the following link: {{{activate.url}}}", 'buddypress' ),
		),
		'core-user-registration-with-blog' => array(
			/* translators: do not remove {} brackets or translate its contents. */
			'post_title'   => __( '[{{{site.name}}}] Activate {{{user-site.url}}}', 'buddypress' ),
			/* translators: do not remove {} brackets or translate its contents. */
			'post_content' => __( "Thanks for registering!\n\nTo complete the activation of your account and site, go to the following link: <a href=\"{{{activate-site.url}}}\">{{{activate-site.url}}}</a>.\n\nAfter you activate, you can visit your site at <a href=\"{{{user-site.url}}}\">{{{user-site.url}}}</a>.", 'buddypress' ),
			/* translators: do not remove {} brackets or translate its contents. */
			'post_excerpt' => __( "Thanks for registering!\n\nTo complete the activation of your account and site, go to the following link: {{{activate-site.url}}}\n\nAfter you activate, you can visit your site at {{{user-site.url}}}.", 'buddypress' ),
		),

STEP 2

a) go to wordpress dashboard, settings, buddypress
b) select and run the ‘repair email’ option

STEP 3

all now works. I have been testing it with dummy users. I hope the whole explanation helps.
Regards