Running the following lisp code:

    (mail-header-parse-address "Łukasz Stelmach <steelman@post.pl>")

yields the error message:

    Unknown symbol: Ł

and the invalid result:

    ("steelman@post.pl" . "ukasz Stelmach")

As far as I can tell this happens if the first character of the address
string is an UTF-8 (non-ascii?) one.

-- 
Było mi bardzo miło.                                  --- Rurku. --- ...
>Łukasz<                                --- To dobrze, że mnie słuchasz.