Rackspace (the company that Point2 uses for email) has an Acceptable Use Policy that creates a restriction of 250 recipients for each message, therefore messages that are sent to more than 250 people will not be sent. Not even the first 250 recipients will get it. The recipient list will first have to be reduced before any emails will be sent successfully. Please note that this is not a daily limit, you can send more than 250 emails per day, just not the exact same email to the same large number of people.
As well, this policy does not allow for the same message to be sent to two groups that together total more than 250 people. It interprets the text of the message and will not allow a second copy to be sent to another large group. Due to this policy they have implemented, Rackspace recommends using iContact, which is a newsletter provider that they partner with or another third party newsletter provider to send messages to groups of this size.