Sending a mail merge campaign is a powerful tool for staying in touch with customers or potential customers, but they still run the risk of being "detected" as a mass email campaign instead of a personalized email campaign. That's because when we normally send person-to-person emails, we respond to the person's previous email instead of starting a new email thread. Pretty much all email campaigns you've ever seen are sent and received as new threads.

GMass, however, allows you to send an email campaign as a reply.