How to only send emails to people who haven't responded?
You can activate email tracking when sending a campaign with Mergo.
Mergo will not only track which emails have been opened or clicked but also for which emails you received a response.
Then you can use the Mergo follow-up feature to send a follow-up email to people who did not respond or did not open your email.
Here are step-by-step instructions to send follow-up emails: