GMass is a Gmail plugin designed for email marketing and automation, ideal for marketers, small businesses, and sales teams. Key features include high-volume email sending, Google Sheets integration, follow-up automation, tracking (opens, clicks, replies), and A/B testing. With competitive pricing starting at $8.95/month, it is cost-effective yet lacks advanced analytics compared to alternatives like Mailchimp or Brevo. It excels in simplicity and usability but may face Gmail sending limits. Customer support is responsive, ensuring a smooth experience for users needing a straightforward mass-emailing tool.