I'm an AWS customer, so I need a separate service for email. I've been using Google Apps for free (we're a small business, and don't have much money to spare), but it's limited to just 10 users. Whilst groups offers a 'hackaround' to support extra email addresses, there are problems with this approach.
Does anyone know of an email provider that is cheaper than Google (ideally, a flat fee for, say, 100 accounts)?