Take a little bit of mobile at a time...
Use the FAX machine...er yeah right, welcome to the 21st century. And how much is that costing a year? And don't talk about reliability, a piece of paper sat in an in-tray is not securely or reliably delivered. And then there's cost: toner, maintenance contracts, paper, phone line rental. Most organisations haven't a clue how much they're spending on fax and when they do calculate it (as I've done on many an occasion) they are shocked at the amount of money they're wasting.
So, mobile email - no, of course it isn't essential. Just like a company website isn't essential, or e-commerce, or business cards, or headed stationery or marketing campaigns... Of course eventually there'll be no business left. Mobile email and mobile working is simply another part of the puzzle. A business can use mobile email to gain (a little) competitive advantage. I use it to make me more efficient, not much, but a little. And every little helps.
And once you have a population of mobile devices with email, you can look to leverage that investment by tacking on other little bits of mobile software that help. Mobile timesheets perhaps? Or mobile access to the company intranet.
Don't go mad. Don't over invest. Bite off a little piece of mobile technology at a time and see how it goes.
The results will speak for themselves.