Still, some rudimentary validation can prevent cases of someone entering the wrong value (e.g., just their username) or an incomplete value (e.g., scott.trudeau

Still, some rudimentary validation can prevent cases of someone entering the wrong value (e.g., just their username) or an incomplete value (e.g., scott.trudeau@gmail ) -- which I see with some regularity ~10k signups/month. If this lowers support email volume by even just 10%, that's not insignificant.