Hi,

The following command brings up a mail composition dialog with blank subject instead of the subject 안 as expected on my system with gawk installed:

xdg-email aaa@aaa.com --subject "안"

However, this works fine on systems that use mawk (such as Feisty). The problem is within the awk code embedded in the url_encode function:

-- snip --
for ( i=1; i<=length ($0); ++i ) {
    c = substr ($0, i, 1)
    if ( ord [c] > 127 ) {
-- snip --

In gawk, string manipulation functions such as length are unicode-aware and return the number of unicode characters instead of the number of bytes. This would usually be a good thing, but in this case the unicode character should be broken up into bytes to be encoded properly. 

Setting LANG and LC_ALL to C right before this snippet tricks awk into thinking the string is ascii and processes it accordingly.