I run an extremely small business, but due to the nature of it, there are a few days a year that my website needs to send a lot of notification emails.  One of those days is coming up and I'm a bit worried about hitting daily outgoing limits.  The emails that are sent are extremely small, but it's the quantity I'm worried about.

I don't mind paying a reasonable fee to temporarily increase the outgoing email count, but I can't really find information anywhere on doing so.  If someone could please help me better understand my options, I'd highly appreciate it.