Sometimes when it goes down it is usually due to a lack of optimization for mobile devices. Keep in mind that most people today use or access this through their mobile devices, not so much through PCs, since people with PCs are usually much smaller than users with mobile devices, so maybe it is due to this. You should check it out.
It's good that you clarify this, because while I already knew and took into account some things, I had no idea that others were like that. Thank you very much for the very specific and detailed clarification.Email marketing click through rate could be down due to various reasons. Not creating a professional mail is one of the main reason why the click through rate could be down. Just think about this. Why would anyone click on a specific mail in case if the mail looks spammy? Having said that, mail templates and the actual mail address also okays a big role. Your email address should look professional. Avoid gmail or yahoo mail at all costs.