Answer:
Revision of Sentences for Conversational and Professional Tone:
1. We're happy to send to you the procedure manuals that you have requested.
2. Please indicate the model number of the appliance to enable us submit your order.
3. BTW Angela didn't take kindly to the accusation that she was pilfering office supplies.
4. Your goods were dispatched on April 15 in line with your email of April 12th.
5. The Manager said the team couldn't meet because of my illness.
6. All employees who desire to change their health plans should do so before December 30.
Explanation:
The combination of conversational and professional style of writing enables the reader to relate with the author. For the reader it is more credible, natural, and easier to understand when the author uses her natural voice, without too much formality.