if you are on a *nix os apparently you can pass an rfc2822 formatted address in the to parameter, but not on windows.
i havnt visited the mail function man page in a while but when i did the other day this part was new..
to
Receiver, or receivers of the mail.
The formatting of this string must comply with RFC 2822. Some examples are:
[email]user@example.com[/email]
[email]user@example.com[/email], [email]anotheruser@example.com[/email]
User <user@example.com>
User <user@example.com>, Another User <anotheruser@example.com>
im not sure if this works for all version or just the latest 4.3.11. but you can try my method too as it worked ok.