Hi, I am new to Express invoice. And i have found initially that making a setup for email sending is little trciky. I have found also many people were reporting the same. Finally i have managed to find the rootcause of these problems. So like to share this solution here, so that it will be helpful for other users. Most of the email sending problem is not from Express Invoice side, it is from our email operator side !!! 1) First we have to adopt the Express Invoice Email sending setting as mentioned in: http://www.nchsoftwa...de/kb/1450.html 2) Additional settings from our email side For Gmail, a) If you use 2 steps verification in your email settings, then you have to USE APPS PASSWORD in Express Invoice, instead of your normal login password. To generate APPS PASSWORD check the following link: https://security.goo...passwords?hl=en Additional we have to Turn Off the option "Disable Access for less secure Apps" (from Security Chekup settings) For other Emails: a) I have not tested for other emails, but i guess most of the modern email provider gives "APPS passowrd" which we have to use it in Express Invoice instead of our normal login password. Hope this information helps.