Returns the HTML email link to the author of the current comment.

Care should be taken to protect the email address and assure that email
harvesters do not capture your commenter’s email address. Most assume that
their email address will not appear in raw form on the site. Doing so will
enable anyone, including those that people don’t want to get the email
address and use it for their own means good and bad.

function get_comment_author_email_link( $linktext = '', $before = '', $after = '', $comment = null ) {
	$comment = get_comment( $comment );

	/**
	 * Filters the comment author's email for display.
	 *
	 * Care should be taken to protect the email address and assure that email
	 * harvesters do not capture your commenter's email address.
	 *
	 * @since 1.2.0
	 * @since 4.1.0 The `$comment` parameter was added.
	 *
	 * @param string     $comment_author_email The comment author's email address.
	 * @param WP_Comment $comment              The comment object.
	 */
	$email = apply_filters( 'comment_email', $comment->comment_author_email, $comment );

	if ( ( ! empty( $email ) ) && ( '@' !== $email ) ) {
		$display = ( '' !== $linktext ) ? $linktext : $email;
		$return  = $before;
		$return .= sprintf( '%2$s', esc_url( 'mailto:' . $email ), esc_html( $display ) );
		$return .= $after;
		return $return;
	} else {
		return '';
	}
}