<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Users\Item\SendMail\SendMailPostRequestBody;
use Microsoft\Graph\Beta\Generated\Models\Message;
use Microsoft\Graph\Beta\Generated\Models\Recipient;
use Microsoft\Graph\Beta\Generated\Models\EmailAddress;
use Microsoft\Graph\Beta\Generated\Models\Mention;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new SendMailPostRequestBody();
$message = new Message();
$message->setSubject('Project kickoff');
$toRecipientsRecipient1 = new Recipient();
$toRecipientsRecipient1EmailAddress = new EmailAddress();
$toRecipientsRecipient1EmailAddress->setName('Samantha Booth');
$toRecipientsRecipient1EmailAddress->setAddress('samanthab@contoso.com');
$toRecipientsRecipient1->setEmailAddress($toRecipientsRecipient1EmailAddress);
$toRecipientsArray []= $toRecipientsRecipient1;
$message->setToRecipients($toRecipientsArray);
$mentionsMention1 = new Mention();
$mentionsMention1Mentioned = new EmailAddress();
$mentionsMention1Mentioned->setName('Dana Swope');
$mentionsMention1Mentioned->setAddress('danas@contoso.com');
$mentionsMention1->setMentioned($mentionsMention1Mentioned);
$mentionsArray []= $mentionsMention1;
$message->setMentions($mentionsArray);
$requestBody->setMessage($message);
$graphServiceClient->me()->sendMail()->post($requestBody)->wait();