Suggestions weighing more a few pounds unworkable. Box can be easily emptied into trash at end of day. Will probably get more gum wrappers that suggestions. Pro - Easy to do from anywhere in the building. Big messages not a problem.
Electronic messages are easy to delete.
Con - Won't be able to strip .signature files from the end of messages. Requires users have access to e-mail. Electronic messages are easy to delete. Pro - No problem with signatures. Con - Requires that users remember command exists.