In OpenERP first, create a database and then install the sale module and account module with mapping your country currency and account module. Then install the mass mailing module in your database and thenconfirme your email templates in mass mailing module.
Follow these step given below
Step1- First we install the module in your database like as sale and account module and then setup of the email configuration the email.
Show email setup given below
Settings -> General Settings -> Outgoing Mail Servers and than create the outgoing mail in your database like as a many point given below:
1- In Description test write Gmail.
2- In SMTP Server test write smtp.gmail.com.
3- In Connection Security select the SSL/TLS.4- In SMTP Port fill is 465.
5- In Username write your gmail is like as email@example.com
6- In Password wtite your gmail password.
Note: this link very use full for configure email
Step2- Then install to the passmailing module in your database and go to Menu like:
Mass Mailing -> Configuration -> Mail Templates and select or create mail Templates
and then mail Templates is Use template to select in invoice. And than send mail for your customer as par requiement format.