This isn't really about websites, but it is to do with online security, so bear with me.
Every now and again I receive an automatic response when I send an email to someone. In my opinion, these auto-responders should be banned. I don't mean that they annoy me. Although it is annoying to receive an email and to waste time opening it only to find that it is an automatic response. But I think they should be banned for the negative effects that they bring to the company or person using them.
There are many sources of spam. Spammers can get hold of your email address from all kinds of sources; sources that you mistakenly trusted or sources that were just irresponsible with your data. Or maybe you just gave your email address to every spammer who wanted it by displaying it in plain view on your website.
So, even if you never respond to spam, they can still make money out of you.
But what if you are out of the office? A lot of people use "out of office" auto responders. These have exactly the same effect.
Most large IT companies ban the use of auto responders and out of office replies. I know from my experience of working at IBM that their employees are only allowed to use out of office responders internally. This means that the out of office response is only sent to emails that come from other employees. So no responses are sent to addresses outside the company which may be a source of spam. This isn't bad, but for much smaller companies, you'll already know if your colleague is out of the office.
A good solution would be to only send out of office responses to a white list of email addresses from your email address book. But I haven't come across any software with that option yet. If you know of any, please let me know.
So in general, if you can avoid using them, I would.