imap_mime_header_decode()
function decodes MIME message header extensions that are non
ASCII text (see
RFC2047) The decoded elements are returned in an array of
objects, where each object has two properties, "charset"
"text". If the element hasn't been encoded, and in
other words is in plain US-ASCII,the "charset" property of
that element is set to "default".
In the above example we would have two elements, whereas
the first element had previously been encoded with
ISO-8859-1, and the second element would be plain
US-ASCII.