When migrating mails. The Estimated number of mails is much lower than the total number of mails. This means that the migration progress bar can get to 100% before the migration is actually completed.
The calculated number of items is taken from the Domino server when you run the directory export.
This means that if the Domino server hasn't been re-cataloged for a long while, the estimate can be very out of date.
The calculated number of items is taken from the Domino server when you run the directory export.
You should be able to increase the accuracy by running a catalog on the Domino server and then perform a new Directory Export in NME.