script copy sender(s) email address only to the clipboard
Yes, AppleScript makes it easily possible ! 

Here is an AppleScript which can do that : 

tell application "Mail"
    set theSenderList to {}
    set theMessages to the selected messages of message viewer 0
    repeat with aMessage in theMessages
        set end of theSenderList to sender of aMessage
    end repeat
    set the clipboard to (theSenderList as rich text)
    beep
end tell


It will cop the mail senders to the clipboard as following: John Doe &lt;John.Doe@gmail.com&gt;



The same script without the names : 

tell application "Mail"
    set theSenderList to {}
    set theMessages to the selected messages of message viewer 0
    repeat with aMessage in theMessages
        set end of theSenderList to (extract address from sender of aMessage)
    end repeat
    set AppleScript's text item delimiters to " "
    set the clipboard to (theSenderList as string)
    set AppleScript's text item delimiters to ""
    beep
end tell


It outputs only the addresses with a space delimiter : john.doe@gmail.com jane.doe@gmail.com



For the beep, just add beep before the end tell (as I already did above).