Question: I have my config/mail 'driver' set to mandrill, host, port, etc. including in services.php mandrill secret set.

Sending Mail works fine locally, but on the live server I get:

> 
> Class 'GuzzleHttp\Client' not found
> 
> 
> 

I have tried "guzzlehttp/guzzle": "~5.3|~6.0", and then back to "guzzlehttp/guzzle": "~4.0", no luck. I have done composer update, and dump-autoload still no luck on my live server. Been through every other associated Stackoverflow question and still can't resolve.

Answer: 
Please follow these simple steps:

**First:** Place this on top of your class

```
use Guzzlehttp\Client;

```

**Second:** Inside your function, instead of using

```
$client = new Client();

```

use

```
$client = new \GuzzleHttp\Client();

```

**reference:**

<http://docs.guzzlephp.org/en/latest/quickstart.html>
try composer require guzzlehttp/guzzle without specifying the version. Worked for me