I've got a couple users getting errors when the calendar tries to give them notification of an upcoming event. They get a "Local Failure Notice" email sent to them. Here's the text from one of the mails:
Local Failures were detected. No action is required.
This e-mail was generated for technical support purposes.
Sync Type: Delta Sync
Store: Zimbra - user name
Computer Name: CS-17
Error Code: -2147467259
Error Message: Unspecified error
For one of the users, I've tried reinstalling her ZCO and recreating the local mail account. (I get Zimbra profile creation errors when I delete her local mail profile and reinstall ZCO.) But no effect on this issue.