UPDATE:
The names imported are unavailable for use in WordPress/Jetpack post notifications. The import failed to add the names to our WordPress Users.
The import DID add the names to a list in the Email Subscribers plugin. The plugin is sending Post Notifications to this list. The Reports tab shows some (a very few) of the Notifications as “Viewed.” The Subscribers list is showing which of the emails has “Unsubscribed.”
When importing we selected the option to “Select Subscribers Email Status: Confirmed.” As a test, we “Unconfirmed” an email address (my own) and attempted to “Resend Confirmation.” The Confirm email has yet to arrive to Inbox or Junk folders.
The test email addy was returned to “Confirmed” status, and Post Notifications are being received.
We would change the review to four stars because some of the functions are working as advertised. If the Resend Confirmations worked for us, it could lead to more of the emails being viewed.