[Dovecot] 100% CPU utilisation

[Zoong Pham]

Dovecot (0.9.11) consumes 100% CPU utilisation when accessing
(either pop or imap) one of my mailboxes. It doesn't happen
with other mailboxes.
The mailbox has about 500 mails while others have many more.
They are all in mbox format.

OS: OpenBSD-3.5 with all patches
MTA: Sendmail-8.12.11
It happened with other RCs of dovecot-0.9.11
Configured as: ./configure --without-pam --without-shadow --without-vpopmail --localstatedir=/var --with-ssldir=/etc/ssl --with-ssl=openssl

There is no strange information in /var/log/maillog except the
normal ones like:
Sep  6 10:12:40 onion imap-login: Login: zoong [127.0.0.1]

The pop or imap clients (mutt and squirrel-1.4.3a) just stay at "opening INBOX ...".
mutt can open directly the mailbox without any problem.
I rebooted the server and problem still happening.

Can someone advise how to find out what's wrong here?
I guess there is some kind of corruption within the mailbox.

Thanks,
Zoong PHAM

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