How to manage accented characters in mail header?

I have a Python script that filters my incoming E-Mail.  It has been
working OK (with various updates and improvements) for many years.

I now have a minor new problem when handling E-Mail with a From: that
has accented characters in it:-

    From: Sébastien Crignon <sebastien.crignon@amvs.fr>


I use Python mailbox to parse the message:-

    import mailbox
    ...
    ...
    msg = mailbox.MaildirMessage(sys.stdin.buffer.read())

Then various mailbox methods to get headers etc.
I use the following to get the From: address:-

    str(msg.get('from', "unknown").lower()

The result has the part with the accented character wrapped as follows:-

    From: =?utf-8?B?U8OpYmFzdGllbiBDcmlnbm9u?= <sebastien.crignon@amvs.fr>


I know I have hit this issue before but I can't rememeber the fix. The
problem I have now is that searching the above doesn't work as
expected. Basically I just need to get rid of the ?utf-8? wrapped bit
altogether as I'm only interested in the 'real' address.  How can I
easily remove the UTF8 section in a way that will work whether or not
it's there?


--
Chris Green
·