RFC2047 in headers

While this works:

admin-> mail -s Hello -E 'set sendmail=sendmail:/home/admin/bin/sendmail' --content-type=text/plain 'CC <[email protected]>' < text

Following does not work:

admin-> mail -s Hello -E 'set sendmail=sendmail:/home/admin/bin/sendmail' --content-type=text/plain 'ČC <[email protected]>' < text
mail: Cannot parse address `ČC <[email protected]>': Malformed email address

Am I supposed to convert the name for email address myself to RFC 2047
string?

Following does work:

mail -s Hello -E 'set sendmail=sendmail:/home/admin/bin/sendmail' --content-type=text/plain "=?utf-8?Q?=C4=8C?= <[email protected]>" < text

But maybe mailutils shall handle that itself to RFC 2047.

I think that subject line also has to be prepared similarly, maybe not
same RFC, maybe not, I have forgotten, but I will find it.

I think that user should be able to enter UTF-8 as for email name and
that such should be converted rather by mailutils.

Jean