Ampersands in e-mail addresses in to, cc, and bcc fields of mailto-URL query strings

"mailto:a%26b%40c.org?to=c%26d%40e.org": This mailto link is correctly URL-escaped, has a "to" field in the query string portion of the URL, and causes NO problem
"mailto:a%26b%40c.org?cc=c%26d%40e.org": This mailto link is correctly URL-escaped, has a "cc" field in the query string portion of the URL, and causes NO problem
"mailto:a%26b%40c.org?bcc=c%26d%40e.org": This mailto link is correctly URL-escaped, has a "bcc" field in the query string portion of the URL, and causes a problem - the percent escapes for the ampersand and @-sign are not removed!