For most people, an email account with bigpond, Yahoo, hotmail or gmail is sufficient for their needs. These email providers will allow large enough mailboxes for most uses. Yet if your needs are more complex, in particular if you want to use your own domain name (such as email@example.com) then you will need to look at paying for this feature. There are many email providers that offer this and other features. I have recently setup a business with Google's service, called Google Apps. As the name implies, it is not just email but a set of cloud services for business collaboration. This includes document sharing, shared calendars and drive space to mention only a few. This is suited to small businesses that don't want to setup their own servers and infrastructure. It is also useful if the business has people spread across many different locations, as the services are located in the cloud (ie. on the internet).
Google charge for their services on a per user basis, which is equivalent to a person. You can have multiple domains or business names per mailbox but only 1 mailbox per person. So you may have firstname.lastname@example.org and email@example.com going to the same mailbox, but if you wanted email to go to another person such as firstname.lastname@example.org then that will require a second user license. Google has flexible options for licensing, either a monthly charge of $5/user/month or you can pay $50/user/annum. The monthly option is useful if you want to have short term employees use an email account for a limited time.