I don't think you can do it. The only way I can see is to copy the whole lot into something like Microsoft Word then choosing "format" - "change case" - "lower case", then copying the whole lot back into Outlook.
Nice one, i might try that in future. I have Word, so i will give it a try next time i do it.
Which will probably be very soon, as the problem is when i use my spreadsheet i have the caps lock on, and i always forget to take it off when replying to e-mails.
Dont laugh, you have all done it...
Have a good xmas and cheers.