pop3d stopped performing login

[Ingo Freund]

Hi,

from one second to the next our cyrus pop3ds service stopped
to login its users, while the imaps side continues its work
properly.
I'm searching and analysing the problem since two days
without success.
Calling the pop3test utility brings normal information into
the logfile (except the login line) and after that the pop3d
process stays in state "read" which I see after doing an
strace on it.
The output of pop3test:
# /usr/bin/pop3test -s -m plain -[a|u] ingo localhost
verify error:num=19:self signed certificate in certificate chain
TLS connection established: TLSv1 with cipher AES256-SHA (256/256 bits)

The imapd logfile shows this:
Jul 11 22:27:55 kd01 pop3s[15981]: accepted connection
Jul 11 22:27:55 kd01 master[16154]: about to exec /usr/cyrus/bin/pop3d
Jul 11 22:27:55 kd01 pop3s[15981]: starttls: TLSv1 with cipher AES256-SHA (256/256 bits new) no authentication
Jul 11 22:27:55 kd01 pop3s[16154]: executed

After that the process stays in the process list for ever
regardless of my CTRL-C.

This happens when I use imtest:

# /usr/bin/imtest -s -m plain -a ingo localhost
verify error:num=19:self signed certificate in certificate chain
TLS connection established: TLSv1 with cipher AES256-SHA (256/256 bits)
S: * OK kd01 Cyrus IMAP4 v2.2.12 server ready
C: C01 CAPABILITY
S: * CAPABILITY IMAP4 IMAP4rev1 ACL QUOTA LITERAL+ MAILBOX-REFERRALS NAMESPACE UIDPLUS ID NO_ATOMIC_RENAME UNSELECT CHILDREN
MULTIAPPEND BINARY SORT THREAD=ORDEREDSUBJECT THREAD=REFERENCES ANNOTATEMORE IDLE AUTH=LOGIN AUTH=PLAIN SASL-IR
S: C01 OK Completed
Please enter your password:
C: A01 AUTHENTICATE PLAIN AGluZ28ARmoxMTAw
S: A01 OK Success (tls protection)
Authenticated.
Security strength factor: 256
C: Q01 LOGOUT
* BYE LOGOUT received
Q01 OK Completed
Connection closed.


I'm running out of ideas, can anyone please help me urgently?
My users are sharpening their knifes already...

TIA
Ingo.
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