using terms from application "Mail"
on perform mail action with messages these_messages for rule this_rule
tell application "Mail"
set the message_count to the count of these_messages
repeat with i from 1 to the message_count
set this_message to item i of these_messages
try
set this_content to (every character of content of this_message) as Unicode text
if this_content is in {"", "?"} then error
on error error_message
set this_content to "NO CONTENT"
end try
end repeat
end tell
end perform mail action with messages
end using terms from