Business Mail is focused primarily on business communication needs, so we do not encourage utilizing it as a platform for email marketing or sending out bulk emails.
To prevent spamming, Business Mail Email limits the number of outgoing and incoming emails per hour and per day.
Outgoing Rate-limit:
Per User: 200 emails/hour, 500 emails/day
Incoming Rate-limit
A recipient can receive up to 500 emails per hour.
Not spamming, but need to send bulk email? We recommend using services like MailChimp or Sendgrid for your email campaigns