Thunderbird: Unknown code IMAP 48

[Antonio]

hi all,

using Thunderbird on Mac some user's have the error "Unknown code IMAP 48". searching
with google and looking in the source I've seen that this message is returned
when Cyrus don't find the error message.

what can I do to find the error and suppress this message ? 

The version is the cyrus-imapd-2.4.14 on FreeBSD 8.1 with murder and
sync_replication.

tanks in advance

Antonio

p.s. sorry for the english

-- 
Never try to teach a pig to sing.
It wastes your time and annoys the pig.