Is it Fair to restrict emails to customers?[for buyers] how about a warning 1st?

[stereo-speakers-refurbished-georgia]

I have a restriction to send emails for 3-4 weeks, i send several emails, because client cant figure out what type of lens he has, a sku oer serial no # wont help. photos not help I cant waste time with people who ccqant take time to figure out weither it is a nikon or cannon mount. for Lens, or Flash