I don't think you find any examples for this type of document. You might ask the committee if they have a preferred format. At any rat, your document needs tobe coherent and flow smoothly. Make sure you put forward your arguments unemotionally.
Try to determine what the committee's business case was for adopting the standards they did. To be successful, you will need to significantly counter their business case.
You probably don't have much of an argument as far as the naming convention goes. All the email administrator would need to do is create aliases using the old naming convention for each user mailbox to enable clients to still reach people using the the old convention. However, the time needed to create these aliases could be used when talking financial aspects of the change.
You will need to prove why Exchange is superior to Groupwise (which means you need to learn everything you can about Groupwise).
You will need to talk about the financial aspects (probably the biggest business reason for doing - or not doing - anything) of changing. What are the costs associated with purchasing and implementing a new email system for your location? Some of these costs are easy to quantify - software purchase, hardware upgrades, training classes, instructional material, etc. Other costs will be difficult to quantify - lost productivity as employees grapple with a new system, time lost migrating users from one system to another, increased support costs during the transition, etc. You need to look long term vs. only immediate costs.