inc/class-Inform_About_Content.php
public function get_members( $current_user_email = NULL, $context = '' ) {

		if ( array_key_exists( 'send_next_group', $this->options[ 'static_options' ] ) ) {
			$user_addresses = $this->options[ 'static_options' ][ 'send_next_group' ];
		} else {
			$meta_key      = $context . '_subscription';
			$meta_value    = '0';
			$meta_compare  = '!=';
			$include_empty = TRUE;

			if ( self::$default_opt_in === FALSE ) {
				$meta_value    = '1';
				$meta_compare  = '=';
				$include_empty = FALSE;
			}

			$users = $this->get_users_by_meta(
				$meta_key, $meta_value, $meta_compare, $include_empty
			);

			$user_addresses = array();
			if ( ! is_array( $users ) || empty( $users ) ) {
				return array();
			}

			foreach ( $users as $user ) {
				if ( $current_user_email === $user->data->user_email ) {
					continue;
				}
				$user_addresses[] = apply_filters( 'iac_single_email_address', $user->data->user_email );
			}
		}

		/**
		 * Filter the list of user email addresses
		 *
		 * @param array $user_addresses
		 *
		 * @return array
		 */
		return apply_filters( 'iac_get_members', $user_addresses );
	}
public function get_members( $current_user_email = NULL, $context = '' ) {

		if ( array_key_exists( 'send_next_group', $this->options[ 'static_options' ] ) ) {
			$user_addresses = $this->options[ 'static_options' ][ 'send_next_group' ];
		} else {
			$meta_key      = $context . '_subscription';
			$meta_value    = '0';
			$meta_compare  = '!=';
			$include_empty = TRUE;

			if ( self::$default_opt_in === FALSE ) {
				$meta_value    = '1';
				$meta_compare  = '=';
				$include_empty = FALSE;
			}

			$users = $this->get_users_by_meta(
				$meta_key, $meta_value, $meta_compare, $include_empty
			);

			$user_addresses = array();
			if ( ! is_array( $users ) || empty( $users ) ) {
				return array();
			}

			foreach ( $users as $user ) {
				if ( $current_user_email === $user->data->user_email ) {
					continue;
				}
				$user_addresses[] = apply_filters( 'iac_single_email_address', $user->data->user_email );
			}
		}

		/**
		 * Filter the list of user email addresses
		 *
		 * @param array $user_addresses
		 *
		 * @return array
		 */
		return apply_filters( 'iac_get_members', $user_addresses );
	}
Get user-mails from all users of a blog by a meta key and the exclusion value ( `!=` operator )

@since  0.0.1
@uses   get_users

@param  string $current_user_email email of user
@param  string $context should be 'comment' or 'post'

@return array $users