An autoresponder for e-mail sends a message back every time a message is received. This is great for when you’re going to be out of the office or away for awhile on vacation, but there are some risks associated with doing this, too.
See, when you have your e-mail program set to automatically respond to every message you get, you send back to everything, including spam messages. All a spammer needs to know is that your e-mail address is valid to open the floodgates for even more spam, and your autoresponse tells them that! In other words, be careful when using autoresponders, or better yet, avoid them altogether!