Number of email send per hour

Number of email send per hour

Hi there,

I am using zoho mail, but if i will send multiple emails in just a short time, I'll get blocked and can't send an email for almost 30 minutes and then I will unblocked it and I am able to send, then after a short time span I will be block again. What is the solution of this? I am glad if you will answer my query, thanks!