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 and 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.
Example 1. imap_mime_header_decode() example
The above example will output:
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.