PersistIQ connects to your email provider (e.g, Gmail, Exchange, Office 365) and emails are sent directly from your email account.
The number of emails you can send is controlled by two factors:
Limits that you set in PersistIQ (daily sending limit)
Limits imposed by your email provider
Your Daily Sending Limits depend on your current plan.
Essentials - 300 emails/day/user (max)
Premium - 600 emails/day/user (max)
Note: Your email provider's daily sending limit still applies. Whatever is lower will take effect. For example, you're on the Premium plan that allows you to send a max of 600 emails/day, but your email provider only allows you to send 350 emails/day, then you'd only be able to send 350 emails/day via PersistIQ.
PersistIQ does not have control over the sending limits that your email provider imposes.
Related article: Video - How to update your PersistIQ daily sending limit.