Almost nothing works in the header.
Although if you hit "reply," weirdly enough, the characters show up correctly in the "Reply to" line at the top. Go figure.
Off Topic » in reply to re: test á, é, Ã, ó, ú, ¿, ¡, Ñ, ñ
Off Topic » in reply to re: test á, é, Ã, ó, ú, ¿, ¡, Ñ, ñ
Although if you hit "reply," weirdly enough, the characters show up correctly in the "Reply to" line at the top. Go figure.