We seem to behaving a problem since upgrading to a new version of CS Cart where returning customers who have previously placed orders and checkout out as guests are being met with a message with words to the effect of 'your email address already exists, log in' but obviously they don't have an account to log in to.
Does anyone have a good/clean solution for a returning “Guest” to be able to use their same e-mail as before during checkout without being blocked by a duplicate e-mail message - Guest customers don’t care about the inner working of why it’s considered a duplicate guest e-mail address, they just want to checkout again doing it their way as a Guest again for whatever reason. This thread is similar to this one: Problem With Checkout As Guest (no real answer there either, the possible solution/suggestion link is a 404 page does not exist now)