These sending limits vary based on email provider type:
- Gmail Free: 350 emails per day
- Google Apps: 1000 emails per day
- Outlook 365: 1000 emails per day
- Generic inbox: 1000 emails per day
HubSpot imposes these limits to ensure that you don't exceed limitations your email provider places upon the number of emails you are allowed to submit to your email server from a remote client. Additionally, we limit daily sends to avoid limitations that ESPs (Email Service Providers, like Gmail) impose upon outgoing and incoming mail to prevent spam.