There are huge benefits to outsourcing your mail.
No single point of failure (power goes out, nic card dies, hard drive failure). All of this results in your mail being down.You do not have to pay for an exchange admin (min of $50k a year to have someone keep your mail server running).
Most hosting company (like the one i work for), have a ton of redundancy built into there networks. Its more more secure then your everyday work networks.
You can save a lot of money also by outsourcing. You never have to worry about hardware failure. No more having to purchase Microsoft Licenses, backup software,antivirus software. You also do not have to pay for that person to keep the server running. That includes everyday maintenance.
You also never have to upgrade. When you outsource, the hosting company do all the upgrades for you.
Also, most your hosting company have Top notch Enterprise security. Specially if the company is SAS70 compliant. They get audited all the time to make sure the customers data is secure and protected.
Also, Spam Filters. Most company’s (at least you should check first), include spam filtering. That is another cost you will have to pay if you keep it in-house.
There are a lot more, and i will be happy to go more in depth in this conversation if you wish. Also, I work for a Hosted Exchange company. If you are interested in talking to me offline about your needs, let me know. I didn’t want to make this just about my company but i wanted to just give you facts on any hosted exchange company you go with.
No matter what company you choose, i believe hosted exchange is a lot better then keeping it inhouse. Just make sure you do your research on the top hosted exchange company before you make your choice.
You can send me a private message if you want to talk offline about your needs and i can at least give you more information about what you need to look for.