Odoo V9 Enterprise; Outgoing mail server: GMail

I have a mass mailing set up to go out to a section of our customers (totaling 3842 contacts). I set up and scheduled the mailing to go out at 9:00AM. Odoo is only sending 80 messages as a time instead of sending them all at once. Is there an option to have them send all at once? I think it may be restricted by Google since we have the outgoing mail server set up with GMail, but not sure where that would be either and if Odoo is restricting it first or not.