Email marketing example

Most of companies like to use E-mail marketing for retention. Opt-in mail marketing is one of E-mail marketing and that is very common. "Opt-in" that's means you are willing to accept the information / promotion materials from designated company.  Once you're opt in, you will receive many promotion mails.

Recently, i have joined "Groupon" member, this company is mainly through out e-mail to promote their new offer, I have received 5- 6 promotion mails from "Groupon" per week in average. The product variety is wide. In general, i will buy / feel interest in 1-2 offers, therefore, i think "Groupon" is one of successful company in using E-mail marketing on promotion, it's generate sales and create customer interest in this.