SMTP IDN # # Server-side # # Client-side smtp idn !win32 LC_ALL=en_US.UTF-8 LC_CTYPE=en_US.UTF-8 perl -MI18N::Langinfo=langinfo,CODESET -e 'die "Needs a UTF-8 locale" if (lc(langinfo(CODESET())) ne "utf-8");' SMTP without SMTPUTF8 support - UTF-8 based sender (host part only) From: different To: another body smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt recipient@example.com --mail-from sender@åäö.se -T - # # Verify data after the test has been "shot" EHLO %TESTNUMBER MAIL FROM: RCPT TO: DATA QUIT From: different To: another body .