Reusing the connection is established with google cript app google and google spreadsheets, they have conducted tests of electronic mail sent availing the services of google.
In this case the ESP8266 sends a series of parameters to google Script Email Address, Subject, Message via the url,
operation is both simple and I think that is simply an option to send any eventuality from your gmail account without much complication. Simply a secure connection with Google script is done and sends a Post with the parameters required
There is another way to send e-mails and tutorials future roadmap send emails via SMTP native from ESP8266.
More information on this project :
Step 1: Programming ESP8266 With Arduino IDE
This tutorial shows how to configure and program the ESP8266 01 from arduino IDE
Step 2: Connection ESP8266 and Google Spreadsheet (Google Docs) Direct
Complete tutorial and explanation about secure connection between ESP8266 and Google App Script.