[exim] From header with encoding not parsed?

[MRob via Exim-users]

Hi, I have a variable to extract the email address in from header set 
like this:

${lc:${address:$h_From:}}
But it comes out blank(empty) given a "from" header like this one:

From: =?utf-8?Q?My=20Bizness=2C=20Inc.?= <charles@*munged*.org>

I think thats a valid header? Did i do somethings wrong please? Thanks!

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