Dear Dan, Thank you for your prompt reply. >> >> >imtest -m GSSAPI imapsv01.grt.citizen.co.jp > > Is that from the same machine/user running thunderbird? > No. I ran the imtest on Linux client using the same principal as on the Windows client. On the Windows client, it was installed with Thuderbird 2.0.0.24 and MIT Kerberos for Windows 3.2.2. Thanks a lot. John Mok ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html