<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Users\Item\Messages\MessagesRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new MessagesRequestBuilderGetRequestConfiguration();
$queryParameters = MessagesRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->filter = "MentionsPreview/IsMentioned eq true";
$queryParameters->select = ["Subject","Sender","ReceivedDateTime","MentionsPreview"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->me()->messages()->get($requestConfiguration)->wait();