Zimbra 8.8.5 seems to freeze up on me periodically. I wrote this script to automatically kick it when it happens to avoid getting calls from users at odd hours complaining that they couldn't check their mail.

kickstucklocks.sh

#!/bin/bash
# Script to automatically restart mailboxd when IMAP mailboxes fail to lock
# (which usually indicates the server has hung)
#
# Configure MAILTO to match where you want the notification email sent.
#
# Prerequisite: You must install LogWarn, which can be found at
# https://github.com/archiecobbs/logwarn if your package manager doesn't have
# it.

MAILTO="nobody@nowhere.tld"

ZMHOSTNAME=`/opt/zimbra/bin/zmhostname`
MESSAGE="To: $MAILTO
From: Zimbra on $ZMHOSTNAME <zimbra@${ZMHOSTNAME}>
Subject: Mailboxd restarted

Mailboxd restarted due to imap lock failures
"

LOGWARN=`/usr/bin/logwarn -d /opt/zimbra/log -p /opt/zimbra/log/mailbox.log 'Failed to lock mailbox'`
if [ -n "$LOGWARN" ]; then
    /opt/zimbra/bin/zmmailboxdctl restart
    echo "$MESSAGE" | /opt/zimbra/common/sbin/sendmail $MAILTO
fi