ERROR: [4970-24-50-00000000] Unable to open mailbox for user 'User@company.com' (4308026)

When migrating mail messages from Notes Migrator for Exchange to Microsoft Exchange you the following error occurs:

ERROR: [4970-24-50-00000000] Unable to open mailbox for user 'user@company.com'
1 User has no PR_EMS_AB_HOME_MDB.

Below are three possible reasons for this error:

1. There are duplicate entries in AD for the record (i.e., one contact and one mailbox-enabled account) and the Migrator is finding the contact first.

2. The Receive As permission on the mailstore for the Migrator's AD mailbox-enabled account referenced in the Exchange profile was also checked Denied. Only the Allowed box can be checked. If this is the case, you may want to create a separate "migadmin" AD mailbox-enable account which only has a membership with the Domain Admins group.

3. The Outlook Address Book was not included as a service in the Migrator's Exchange profile.