how do I check gmail_address using GMAIL API in php

Question

I am using gmail api in php application. While I send mail using the sender_email it returns that invalid email. I have a table sender_email: in this table I enlisted all gmail address.

I need to check the email is valid or not :: If not valid then update the table sender_email for the gmail adresss and then it will find another gmail address which is valid. This is continous process.

Here is the code for checking emails using gmail api::

public static function check_gmail_authentication($from_email, $auth_token){
    while (true)
    {
        try
        {
            $result = GmailSendMessage::re_check_gmail_authentication($from_email, $auth_token);
            if($result == null){
                DB::table('sender_email')->where('email', $from_email)->update(['status' => 'invalid']);
                $sender_email = SenderEmail::where('status','=', 'public')->where('api_type', 'google')->first();
                $from_email = $sender_email->auth_token;
                $auth_token = $sender_email->email;

                //again try
                $result = GmailSendMessage::check_gmail_authentication($from_email, $auth_token);
            }
            break;
        }
        catch(Exception $e)
        {
            print_r($e->getMessage() . ' - failed. Retrying...');
            continue;
        }
    }
}

and re-checking the method in same controller::

public static function re_check_gmail_authentication($from_email, $auth_token){

    //Google client
    $client = new Google_Client();
    $client->setAuthConfigFile(public_path() . '/apis/api_for_sender_email.json');
    $client->setLoginHint($from_email);
    $client->setAccessType('offline');
    $json_token = $auth_token;

    try {
        $client->setAccessToken($json_token);
        // If access token is not valid use refresh token
        if ($client->isAccessTokenExpired()) {
            $refresh_token = $client->getRefreshToken();
            $client->refreshToken($refresh_token);
        }
        return $from_email;
    } catch (\Exception $e) {
        return false;
    }
}

Parameter $from_email = gmail address and $auth_token = access token.

Issue :: My code returns NULL

What I want ::

1. I need a valid email
2. I need to update invalid email in the sender_eamil table

Please help me how do I get valid email using while loop. Thanks in advanced.