I have this problem too.
Correct Answer by David Hailey about 6 years 1 month ago
From reading your post, I assume you are just confused over what this message means and why you see it in the logs...so here goes:
Begin resynching subscriber mailboxes. %1 mailboxes are scheduled for synchronization.
This is a system log message that is seen when a scheduled MWI resync begins on Unity. This is fairly normal as many companies have their VM system configured to resync MWI during off-hours to take care of any potential issues with sync during the day.
If you go to Unity Tools Depot and open the UTIM (Unity Telephony Integration Manager), you can look at your Unity to CUCM integration and see that most likely the check box for "MWI Resynchronization" is checked and then a time is specified for when the resync should start each evening.
If you watch the logs, you should see this message as a starting process and eventually you'll see a completion message.
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