> As a side issue here I can't believe sniffing is still the default It isn't the default in modern browsers, or at least not in the sense you mean. The header

> As a side issue here I can't believe sniffing is still the default It isn't the default in modern browsers, or at least not in the sense you mean. The header still controls some things, but even without it, browsers will not sniff something served as content type image/png as html or anything like that. How modern browsers interpret that is different than IE.