T.K.
You run a business in 2011. If you aren't instantly available, the next guy will be. You should give yourself every possible tool to be competitive. Businesses that don't adapt, don't thrive.
One creative solution is to set an autoreply on your email. Everytime someone emails you they will get your response instantly. You can set it to say something Like Thank you for your email, I will be sewing until 4 and will return all messages between 4 and 6. Or get creative with it. Like "a stitch in time saves 9" Thanks for your time but I am busy stitching, will return your message this afternoon.