Editor's note: disabling SSL verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint such as Gmail, and you'll be vulnerable to a Man-in-the-Middle Attack.
Be sure you fully understand the security issues before using this as a solution.
Easy fix for this might be editing config/mail.php and turning off TLS
'encryption' => env('MAIL_ENCRYPTION', ''), //'tls'),
Basically by doing this
$options['ssl']['verify_peer'] = FALSE;
$options['ssl']['verify_peer_name'] = FALSE;
You should loose security also, but in first option there is no need to dive into Vendor's code.