[Exim] Using the textual part of email address

The RFC 822 mailbox specification permits an identifying phrase in addition
to the "real" email address, for example
Ross Boylan <xfq@???>
has "Ross Boylan" (that's what I mean by the "textual part" in the subject;
I know it's all text).

I would like to use this in my exim filter. I know it's in the message
headers, but does it ever appear anywhere else?

For example, does the envelope information ever include this?
Do exim's per address macros (e.g., $local_part) include this?

My impression is that the answer to both questions is "No."

The reason I'm interested in this is that I have one address that I'm using
for myself and my wife, and I'd like to pick out mail to her based on the
identifying phrase. I am also planning on doing some mailing list type
things, and would like to do something similar with them. I use a dial-up ISP.

At the moment I'm using a system-wide address filter (the one that works on
a per-address, rather than per message basis)* to identify things with my
wife's name in the headers. This is probably serviceable, but can get
screwed up in a number of ways. The underlying problem is that I don't
know which of the entries in the message header (if any) is actually the
source of the particular address the filter is handling, so it may focus on
an irrelevant address. For example
To: karenWhoIsNotMyWife@???
Cc: RossBoylan@???
When the cc comes back to me, the filter detects that delivery is to me and
that a header includes the string "karen" (my wife's name). It concludes
the message is intended for her, and sends it to her.

Or suppose I send a reminder to both of us
To: "Karen" <RossBoylan@???>, "Ross"
<RossBoylan@???>
In this case 2 copies go to my wife's (local) account (though I guess exim
detects the duplicate and nukes it)?

I know this is all very hokey, and that in a perfect world we would have a
fixed domain to which I could attach arbitrary local names, but I
don't. My current ISP allows me several mailboxes, but I don't want to
give them out as permanent contacts in case I switch ISPs. I also know
these kind of personal uses are not exim's intended target. But I'm using
it, so I thought I'd ask!

By the way, I just got the Exim book, and I'd like to thank Philip for
writing it. In particular, chapter 2 looks as if it will finally fill in
some holes in my knowledge.

(*) I tried a system filter, but when I sent mail to karen@??? it saw
the karen and executed the filter (deliver to her locally) so she never got
the message. The address filters only kick in for local delivery, and so
are saner.