It's not clear in your description if this issue is occurring for all users, a particular user, or particular group of users that reside on a particular target mail server.
There is really not enough information in your description that will give you more than you already know.
The provisioning task is attempting to modify the profile doc in a mail file and can not complete the operation in a timely manner.
I would recommend the following:
1) Review the event logs for errors occurring during the time provisioning processes.
2) Review the entire provisioning reports in order to determine patterns of failure.
Is it consitently a single user that fails?
Is it a group of users that fail? If it is the same group determine commonalities between them.
Are they on the same target server? Same OU? Same target region?
3) Gather a dtrace of the evlotusdominopolicysynch task during a provisioning run.
If it is just a particular user that is failing then you can gather that dtrace and run the process against that user.
You may need some assistance analyzing this information but may not be able to share that info. here so you may need to call in a support case if you can't share the information here.
It is usually difficult to determine what the root cause of the issue is by just looking at a single error.
It generally takes looking at all the evidence in context in order to get to the bottom of it.
