Returns true if user with given email (userEmail) is known in the database, or the Super User

@param string $userEmail
@return bool true if the user is known
968640
public function userEmailExists($userEmail)
    {
        Piwik::checkUserIsNotAnonymous();
        Piwik::checkUserHasSomeViewAccess();

        return $this->model->userEmailExists($userEmail);
    }
913511
public function isRole($email)
    {
        if (! $this->isEmail($email)) {
            return null;
        }

        $user = $this->userFromEmail($email);

        if ($user) {
            // Load disposable domains
            if (is_null($this->role)) {
                $this->role = include('data/role.php');
            }

            // Search array for hostname
            if (in_array($user, $this->role)) {
                return true;
            }

            return false;
        }

        return null;
    }
97008
public static function isSuperUser($user = ''){
		$superUser = self::getSuperUserConfig();
		if(!$user){
			$user = self::getCurrentUsername();
		}
		if($user && in_array($user,$superUser)){
			return true;
		}
		return false;
	}
207591
public function setEmail($email): User
    {
        if ($this->email !== $email) {
            $this->email = $email;

            DB::table('user')
                ->where('user_id', '=', $this->user_id)
                ->update([
                    'email' => $email,
                ]);
        }

        return $this;
    }
898772
public static function isEmail($email)
    {
        $pattern = "/^([0-9A-Za-z\\-_\\.]+)@([0-9a-z]+\\.[a-z]{2,3}(\\.[a-z]{2})?)$/i";
        if (is_string($email) && preg_match($pattern, $email)) {
            return true;
        }

        return false;
    }
1254747
public static function isExistByEmail( $email ) {

		$user = self::find()->where( 'email=:email', [ ':email' => $email ] )->one();

		return isset( $user );
	}
48239
public function filterEmail($email)
    {
        foreach ($this->filters as $filter) {
            $shouldKeepEmail = $filter->checkEmail($email);
            if (!$shouldKeepEmail) {
                return true;
            }
        }

        return false;
    }
826951
public function isAdmin(?string $email = null): bool
    {
        if ($email === null) {
            return false;
        }
        return in_array($email, $this->getConfig()['admin']);
    }
102214
private function findUser($email)
    {
        $response = $this->call($this->tyrUrl . '/' . $this->version . '/users/?email=' . $email);

        $user = json_decode($response);
        if (!empty($user)) {
            return $user[0];
        }

        return false;
    }
1158454
public function iHaveUser($username)
    {
        $email = $this->findNonExistingUserEmail($username);
        $password = $username;
        $user = $this->ensureUserExists($username, $email, $password);
    }
371013
public static function isUser(string $username): bool {
		$userdbname = setup::getValidation("username");
		if (R::findOne('user', ' ' . $userdbname . ' = ? ', [$username])) {
			return true;
		}

		return false;
	}
461575
public function findUserByEmail($email)
    {
        $qb = $this->createQueryBuilder('user')
            ->where('user.email=:email');

        $query = $qb->getQuery();
        $query->setParameter('email', $email);

        return $query->getSingleResult();
    }
976505
public function activateUser($email, $activationKey)
    {
        if ($this->validateActivationKey($email, $activationKey)) {
            $user = $this->findByEmailAndActivationKey($email, $activationKey)->first();

            if ($user->active == 0) {
                $user->active = 1;
                $user->activation_key = null;
                if ($this->save($user)) {
                    return true;
                }
            }
        }

        return false;
    }
1119569
public function isIgnoredBy($userId)
    {
        if ((new Query)->select('id')->from('{{%podium_user_ignore}}')->where([
                'user_id' => $userId,
                'ignored_id' => $this->id
            ])->exists()) {
            return true;
        }
        return false;
    }
464224
public static function getByEmail($email)
    {
        $fields = self::getDbConnection()->fetchAssoc('SELECT * FROM '.User::TABLE.' WHERE email = ?', array($email));
        if (!$fields) return false;
        return self::fetch($fields);       
  	}
212182
public function isSendable($email)
    {
        // Does it look like an email address?
        if (! $this->isEmail($email)) {
            return false;
        }

        // Is is an example domain?
        if ($this->isExample($email)) {
            return false;
        }

        // Does it have an MX record?
        if (! $this->hasMx($email)) {
            return false;
        }

        return true;
    }
1240637
public static function isEmail($email = null)
    {
        if (is_null($email) || !$email || !is_string($email)) {
            return false;
        }
        return (bool) (preg_match('/^[^0-9][A-z0-9_]+([.][A-z0-9_]+)*[@][A-z0-9_]+([.][A-z0-9_]+)*[.][A-z]{2,4}$/', $email) > 0);
    }