NOTE

In some rare instances, you may encounter a contact who is opted into CU emails, opted into your preference, captured in your campaign/report/data extension, and isn't receiving emails.

One possible reason is that the contact has an email address that is being blocked by List Detective. List Detective is a Marketing Cloud tool that maintains info on email addresses and domains that could cause send deliverability problems. One of the validation rules that List Detective uses is to mark email addresses as spam if the username - the part before the @ - of the email address is a prohibited role-based word (ex. feedback@, subscribe@, info@).

The email address will only be blocked if there are no other words or characters with the prohibited word (ex. collegefeedback@ wouldn't be blocked). If a contact has an email address with a prohibited role-based word as the username, they will not receive emails or have a subscriber record in Marketing Cloud.

The solution in this instance is to ask the contact if they have an alternative email address they can use and update their email address in Salesforce.