--Get time setting for action to occur
set t to "3:16:30 PM"
--build a time string to use as a target.
set cd to (current date) as text
set AppleScript's text item delimiters to " "
set targetTime to text items 1 thru -3 of cd
set targetTime to date ((targetTime as text) & " " & t)
repeat while (current date) < targetTime
beep
delay 30 -- check the time every 30 seconds
end repeat
tell application "Mail"
quit
end tell