No, one primary domain & unlimited addon / sub domains (which function just like a primary domain). Here's the first page of my addon domains
The addon domains are created as sub-directories of your primary domain & share the same resources as your primary domain. I wouldn't dream of hosting production sites like this, but for email it's perfectly fine.
BTW, I'm not pushing hostgator, but they were the cheapest I found at the time. Namecheap also offers unlimited addon domains. I'm pretty sure GoDaddy does not.