Vocus.io is a suite of Gmail tools for sales & client success teams.
It comes with powerful email tracking abilities that support per-recipient tracking, link click tracking, branded URLs, and more. Since it's built for outreaches, it supports bulk email campaigns via mail merge. You can even add followup sequences and attach files.
The bundle includes also includes auto-followups (if no reply), CRM integration (with native Salesforce support), templates, email address verification, and much more.