Some people on my e-mail list have determined that every piece of communication requires a response. You probably know these people. You send them an e-mail such as: "Just wanted to let everyone know, Jane said she is going to be coming in a half hour late this morning", to which you immediately receive the reply email: "Thanks"
I think about 10% of my e-mail some days is from these "auto-responders". I propose a rule for all e-mail servers that any e-mail that consists entirely of "Thanks" or "No Problem" is just automatically deleted.
Note: I know you're thinking about it, so be warned that any one-word comments to this post are subject to deletion.