configure 1and1 mail on google cloud platform with laravel 5

I have setup an instance in google cloud platform. I am running laravel 5.2 project on that instance. Everything is working good but i am facing some issues while configuring 1and1 mail.

I know that google cloud platform is blocked the 587,465 and 25 port by default and we can setup some vpn which will help to remove this restriction. But i don't want to go in that way because it would have security problems.

I have tried to send email through smtp and mail driver. I am getting connection failure error through smtp driver, and through mail driver, it shows that email is sent but i am not getting the email in my inbox. Here is my .env file for mail driver settings for 1and1. I have also tried 25 port also.

MAIL_DRIVER=mail
MAIL_HOST=auth.smtp.1and1.co.uk
MAIL_PORT=587
MAIL_USERNAME=test@mydomain.com
MAIL_PASSWORD=pass
MAIL_ENCRYPTION=tls

Can you please help me to configure it?

via Chebli Mohamed