Through App42 Email Service you can send mail to your friends.
For that you need to configure your gmail account with App42 either using Create Email Confirguration api or using App42HQ Management Console.
Configure your gmail account with right parameter parameter as i explained below:
password = "*********", // Password of email address from which you want to send mail
host = "smtp.gmail.com", // For Gmail account host is this.
port = 465
Let me know if you are having any issue with this.