Comment by chaps

Sorry, that's not me. They were more than welcome to fire me as a client.

I've been oncall for long enough in my career to know that a "quick email" is not, really, a "quick" email. It can completely derail everything you do for the day. If on-request work takes five minutes to write an email, then that time includes reading the email, thinking about the email, responding to the email, the cost of derailment of other contract work, the cost of getting back into that other contract work, the research needed to tell them "no". Again, it's about setting boundaries with the client.