When migrating more than one thread, all users after the first report the error;
ERROR: [4965-24-45-8004011D] Unable to open target mail store
MAPI error 8004011D
Error: Microsoft Exchange is not available. Either there are network problems or the Exchange server is down for maintenance.
Component: Microsoft Exchange Information Store
Low level error: 80040115
Firewall between NME (Notes Migrator for Exchange) and Exchange console.
Verify there are no Windows firewall services running between or on NME and Exchange servers, during the migration.