Source Reference:

• Component: bbPress :: bbp-topic

  File: /bbp-includes/bbp-topic-template.php :: Trac Source Line: 1357

  			// Get email from post meta
  			$author_email = get_post_meta( $topic_id, '_bbp_anonymous_email', true );
  
  			// Sanity check for missing email address
  			if ( empty( $author_email ) ) {
  				$author_email = '';
  			}
  		}
  
  		return apply_filters( 'bbp_get_topic_author_email', $author_email, $topic_id );
  	}
  
  /**
   * Output the title of the forum a topic belongs to
   *
   * @since bbPress (r2485)
   *
   * @param int $topic_id Optional. Topic id
   * @uses bbp_get_topic_forum_title() To get the topic's forum title
   */