Practical example of using AppleScript to generate a random number.
OS version:
tell application "Mail"
set myfolder to "zBook giveaway"
set mycount to the count of messages of mailbox myfolder
set randNum to (random number from 1 to mycount)
set mysender to sender of message randNum of mailbox myfolder as text
display dialog "the winner is: " & mysender
set the clipboard to mysender
end tell