You're most welcome.
The mail address mangling should be pretty good, because, basically, nothing in your form looks like an email address.
Conceivably, a spambot could look for a field call "recipients" and then the spambot writer could try and figure out your mangling characters, and demangle it.
But, if your mangling is different from other peoples, then his job is endless.
Remember, it's OK to use email-valid characters for your mangling, like this:
where the AT_MANGLE is "thatismangled", is converted to:
With these infinite possibilities and no particular rule, the spambot's writer's job is impossible.