Every shared web hosting set a limit on how many emails you can send out each hour. The email sending limit is there for prevent email spamming from domain hosted, and to prevent high server load caused by email SMTP process trying to send out email messages.
What is the email sending limits?
For Just Host shared hosting their email sending limit is set to 200 emails sending per hour. If you require higher limits and really need to send out more emails per hours, you can contact support team and asking them to give higher email sending limits to your hosting account.
For higher capacity of email sending per hour, webmaster usually seek higher web hosting plan to provide the processing power and email services. This includes the upgrade to VPS web hosting and dedicated server hosting which give the ultimate resources and faster email sending per hour. For extreme users that demanding million of email sending, the only solution is to setup own SMTP server and DNS server proxy, and this configuration will allows million of email broadcasting per day. Its how the email marketing works and how they send out million of emails each day. Note that sending unsolicited email is illegal and always make sure your email is categorized as spam e-mails.