How can we verify that CiviCRM emails are actually being received. The report shows that all were successfully delivered. However, recipient members are complaining that they aren't receiving the eMails. They also checked their SPAM folders. Not there.
This depends a bit on how you're sending emails. Are you using a mailing service, or do you run your own mail server?
Some mail processors accept mail but then don't allow it through to the user if they don't like the look of it. We had this problem with Outlook/Hotmail at one point. In the end we had to contact them directly to resolve the issue.
There are a couple of things to try if you haven't tried them already:
Check the spamminess of your emails using mail-tester.com. Aim for 10.
Set up Dmarc. This will give you direct feedback from the mail processors (sometimes including instructions/contacts for resolving problems), and it should generally help your mailing reputation.
I would recommend using a mailing service (plenty on the market) as SMTP gateway because they usually provide an admin interface to log the mailing activity that is very accurate. Sometimes CiviCRM activity log says that the email was sent but then you'll discover it was bounced after "getting out" of CiviCRM and CiviCRM doesn't trace this. They will also provide DKIM/SPF entries for your DNS that will dramatically improve the deliverability of your emails (both email and mailing campaigns).