Anytime you autoreply to email, it means a spammer can spoof the sender and spam you with hundreds of emails, which you will faithfully reply with "This address is not monitored" - but you're sending those replies out to people who didn't send them to you, and typically attaching the original message, meaning the spammers get a free spam reflection service from you - you sending their spam to all those people.

So please don't use autoresponders.