We had someone today that sent an inquiry about something (this person is not a client, more of an outside business partner). Dude sent, within about an hour and a half time frame, 7 emails. Calling out one person on the DL multiple times within a half hour, then proceeding to call out the rest of the DLs (ALL in the original copy list) to try to get an answer to his question.
Not every vacation you take is going to leave you completely unreachable. For those days when you’re out of the office but are still checking and responding to email or phone calls, make sure your message explicitly states that people will still be able to reach you, and how:

Proof that some people just Don’t Get It: in response to my out of office voicemail message directing callers to contact my co-worker for anything urgent, a woman left the following message on MY voicemail: “Co-worker, I am having this issue, blah, blah, blah. Please call me at X.” Yeah, I–not co-worker–got the message a week later when I returned.
Thanks for your message! I am brushing up on my social networking savvy and analytics knowledge at a digital media conference in Vancouver from May 1-6. I will have limited email access, so if you need immediate assistance, please reach out to our marketing assistant, Kennedy Tran, at [email protected] or 555-432-6100. In the meantime, if you need access to our media kit, you can find it here.